The Mayor's draft water strategy - london.gov.uk - Greater London ...

August 2009
The Mayor’s draft water strategy
Draft for public consultation

August 2009
The Mayor’s draft water strategy
Draft for public consultation

2 The Mayor’s draft water strategy
Copyright Greater London Authority August 2009 | ISBN 978 1 85261 284 1
Published by Greater London Authority, City Hall, The Queen’s Walk, London SE1 2AA
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Contents
Mayor’s foreword ............................................................................................................. 5
Executive summary .......................................................................................................... 7
1 Introduction ................................................................................................................... 15
Arrangement of this document ................................................................................................ 15
Integrated water management ................................................................................................. 15
Governance of water ............................................................................................................... 17
Links with other plans and strategies ....................................................................................... 18
Towards sustainable development ........................................................................................... 21
Implementation and monitoring .............................................................................................. 23
2 Pressure on water resources ........................................................................................ 25
Introduction............................................................................................................................. 25
Water efficiency ....................................................................................................................... 35
New resources ......................................................................................................................... 36
The effects of climate change .................................................................................................. 38
3 Managing water use ..................................................................................................... 41
Leakage ................................................................................................................................... 41
Demand management ............................................................................................................. 46
Drinking water quality and bottled water ................................................................................ 57
4 Managing rainwater ..................................................................................................... 59
Rainwater use ......................................................................................................................... 60
Managing surface water runoff................................................................................................ 61
Risks of flooding...................................................................................................................... 62
Flooding from the surface water drains ................................................................................... 63
Flooding from groundwater ..................................................................................................... 64
Diffuse pollution ...................................................................................................................... 67
Water Framework Directive ...................................................................................................... 67
Rivers and canals ..................................................................................................................... 67

5 Disposal of wastewater in London ................................................................................ 69
Combined sewers ..................................................................................................................... 71
Flooding from sewers .............................................................................................................. 74
Misconnection of the foul sewer and surface drains ................................................................ 75
Fat, oil and grease ................................................................................................................... 76
Wastewater management and energy ...................................................................................... 77
Sludge management ................................................................................................................ 77
Odour nuisance ....................................................................................................................... 79
6 Paying for water services ............................................................................................. 81
Regulation of water services .................................................................................................... 83
Customers’ willingness to pay .................................................................................................. 85
Setting leakage targets ............................................................................................................ 85
Thames Tideway tunnel and treatment .................................................................................... 86
Charging for water ................................................................................................................... 87
Appendix ....................................................................................................................... 91

Mayor’s foreword
My goal for London is to ensure that it
meets the highest environmental standards
to preserve and protect our citizens’ quality
of life, leading the world in its approach to
tackling the challenges of the 21st century.
And nowhere is this more vital than in the
safeguarding of the capital’s water resources
in the face of a steadily growing population, a
more competitive global business environment
and a changing climate.
London has been at the forefront of water
technology thanks to the engineering genius of
the Victorians who provided us with the world’s
most advanced water and drainage systems.
Now, half our creaky water mains are more than
100 years old and a quarter of the precious
water supplied to our city is lost through
leakage despite steady progress in stemming
these losses in recent years. The sewage system
regularly overflows into the Thames, one of
our finest assets, producing a threat to the
myriad flora and fauna that the river supports
whilst compromising its value as an invaluable
recreational and sporting resource.
London already receives about the same rainfall
every year as Barcelona and the projected
shifts in our climate during the coming
decades will see hotter, drier summers and
warmer, wetter winters. In 2005 and 2006 we
had an exceptionally dry spell which brought
restrictions on our water use and highlighted
how finely balanced our water resources are.
We are fortunate in that we have enough water
to serve our city’s needs, but only if we use it
wisely and effectively.
Becoming more water wise is common sense -
not only to us as individual Londoners, but for
the health and wealth of the city as a whole.
As our city grows and climate change bites, we
will need to use less water more efficiently.
We face a clear choice: to make the water we
have go further, or to pay for prohibitively
expensive new ways to secure water such as a
new reservoir.
If the average Londoner reduced their water
use by just 10 per cent a day we could save an
incredible 48 Olympic-sized swimming pools
worth of water every day. These savings would
also be felt in our pockets - using a water
efficient showerhead plus taking a slightly
shorter shower could save up to £166 for
a typical household energy and water bills,
if they are fitted with a water meter. Water
efficiency provides triple savings - saving
once by not paying for water we don’t use,
saving twice by not heating water we don’t
require and finally saving a third time by
avoiding water infrastructure we don’t need.

6 The Mayor’s draft water strategy
It will also help tackle climate change and the
consequences for our water supply it presents.
We will be helping Londoners save water
through a programme to be launched next
year which will make up to 1.8 million homes
more water and energy efficient. This could
save households each year an average of £62
off bills, equalling a not insignificant 46,000
litres of water and half a ton of carbon per
home. This strategy contains other proposals
to ensure London doesn’t experience water
shortages in the future.
I would like to thank those who have contributed
to this draft strategy to date notably the
Environment Agency and Thames Water. I now
warmly welcome comments and views to develop
the detailed proposals contained here.
Boris Johnson
Mayor of London

Executive summary
1 Most people in London expect to turn on
the tap and get water without having to
think about where it comes from. Equally,
people want to be able to pull out the plug
and let water run away without having to
worry about what happens to it afterwards.
However, changes are going on around us
that mean that Londoners will need to think
more about where water comes from and
goes to.
2 London is a growing city, served by four
different water companies, with much of
the infrastructure more than 150 years old.
This strategy is intended to complement the
plans and strategies of other organisations,
including the national water strategy Future
Water, by presenting a London-specific
view of water management. It draws on the
other plans and strategies but also seeks to
influence their future development. Its goal
is improved water management – both in
terms of the water we want (such as drinking
water) and the water we don’t want (such as
sewage and floodwater in the wrong place).
Arrangement of this document
3 The first chapter gives a general explanation
of the context within which this strategy
is being prepared. The next two chapters
are concerned with the supply of water for
use in homes and businesses. Chapter 2
explains where our water comes from, and
the balance between supply and demand,
whilst Chapter 3 focuses on our use of water
and how we might use the water that we
have more effectively. After that, attention
shifts to how to manage the water that we
no longer need. Chapter 4 is concerned with
rainwater and other surface water whilst
Chapter 5 is concerned with wastewater
collection, treatment and disposal. Chapter 6
explains how water services are paid for.
Chapter 2 – Pressure on water resources
4 The majority of London’s water supplies
come from the rivers Thames and Lee, with
about 80 per cent of all the water being
taken from the freshwater River Thames
upstream of Teddington Weir. It is then
stored in reservoirs around the capital. The
remainder is abstracted from the aquifer that
lies below London.
5 In 2007 Defra asked the Environment
Agency to consider which parts of the
country were water stressed – where water
demand is a high proportion of the rainfall
available to meet that demand. The Agency
categorised London, along with much of
the South East, as an area of ‘serious’ water
stress. To avoid running out of water, or
damaging the environment by abstracting
too much water (for example, by reducing
river flows to a level where fish cannot
survive), it is essential to balance supply
and demand. During most years, including
most summers and dry periods, there is
enough water in the rivers Thames and Lee
together with groundwater to meet London’s
needs. However, during prolonged periods
of low rainfall, supplies are limited and
the water companies may need to restrict
non-essential uses of water, such as garden
watering and washing cars.

8 The Mayor’s draft water strategy
6 This is the situation now, but the climate
is changing. Eight out of the ten warmest
years on record have occurred since 1990.
By the middle of the century, the UK Climate
Projections suggest that average summer
temperatures will increase by 2.7°C and
winter temperatures by 2.2°C. Average
summer rainfall will decrease by 18 per cent
and winter rainfall increase by 15 per cent,
but the overall amount of rain is not
expected to change. These changes will have
a significant effect on the availability of, and
demand for, water.
7 London’s population is steadily growing,
and is expected to rise from the present
7.56 million to between 8.79 and
9.11 million by 2031. The number of
households will grow faster than the overall
population as the average household size is
falling, due mainly to later marriage, fewer
children, more divorce and longer lives. This
growth means increased demand so more
water will have to be supplied, more sewage
treated, and the building of more homes
for this growing population will mean more
surface water runoff.
8 Water companies are required to prepare
Water Resources Management Plans which
set out how each company intend to meet
its customers’ need for water over the next
25 years while protecting the environment.
They are reviewed annually and revised
every five years. In addition, water
companies have drought plans that set out
what actions they would take under various
drought conditions. Finally, every five years,
the water companies also prepare business
plans for approval by the Water Services
Regulation Authority (Ofwat), the economic
regulator of the water industry.
Proposal 1
The Mayor will work with the water
companies, the Environment Agency and
other partners in seeking the effective
management of London’s existing and future
water resources to meet the needs of the
growing population whilst protecting the
natural environment.
Chapter 3 – Managing water use
9 It is all too easy to take secure water
supplies for granted. Londoners rely on
the water companies to provide sufficient
clean water for their needs. However, the
drought of 2006, with associated widespread
hosepipe bans and a real risk of more serious
restrictions was a powerful reminder to us all
that our water resources are not limitless.
10 One-third of London’s water mains are over
150 years old. After decades of underinvestment,
much work is now underway
in London with Thames Water expecting to
have replaced 2,048 kilometres (or nearly
seven per cent) of its mains by 2010, and
a further 2,097 kilometres between 2010
and 2015. However, under Ofwat’s draft
price limits for 2010 to 2015 (see paragraph
29), Thames Water would only be able to
replace 1097 kilometres. Replacing the
mains inevitably affects traffic and the
Mayor wants to minimise hold-ups. He has
therefore agreed a code of conduct with

the utility companies to improve working
practices. Thames Water has also agreed to
start plating sites where work is temporarily
halted, so traffic can flow smoothly.
11 Thames Water has proposed a long-term
objective of reducing leakage in London from
the current (2007/08) figure of 217 litres
per property per day to 114 litres in 2030-
2035. The Mayor considers that Thames
Water’s long-term aim should now be to
achieve the best UK standard of 80 litres per
property per day. Thames Water argues that
such a target is not justified economically.
However, the 25-year time scale of the Water
Resources Management Plans should allow
for significant improvements to be achieved
in the cost-effectiveness of leak reductions
and mains renewal.
Proposal 2
Thames Water should, through its Water
Resources Management Plan, aim to achieve
the best UK industry standard for leakage by
2035, in order to bring London in line with the
best standards of world cities.
12 In London, 23 per cent of households have
water meters. Research has shown that
household metering reduces water use by
between ten and 15 per cent. London’s
currently low level of metering is often
attributed to London’s high proportion
of flats, which are often difficult to meter
individually. However, without widespread
metering (and the correct tariffs to protect
the most vulnerable households) Londoners
are unlikely to be motivated to install water
saving devices and adopt water efficient
behaviour, thereby saving water and
reducing carbon emissions.
Proposal 3
The Mayor will work with water companies and
other partners to support the introduction of
water metering throughout London. The Mayor
considers that all houses in London should
have meters installed by 2015, and all blocks
of flats by 2020. All new flats in London should
have an individually metered water supply.
Tariff arrangements should encourage the
efficient use of water but protect vulnerable
and low-income households.
13 The government’s Code for Sustainable
Homes was introduced to improve sustainable
home building practices. All publicly funded
developments are now required to attain Code
Level 3 (equal to or less than 105 litres per
person per day (l/p/d)) and will be required
to meet Code Level 6 (80 l/p/d) from 2016
onwards. Other housing has to meet less
stringent standards under Part G of the
Building Regulations which, from October
2009, will set a maximum daily usage standard
of 125 l/p/d. This is welcomed, but the Mayor
considers that more ambitious standards are
appropriate for new homes, given that London
is designated as being in an area of serious
water stress.
Proposal 4
The Mayor believes that, where possible, all
new homes should meet the highest level of
the Code for Sustainable Homes for water
consumption
9

10 The Mayor’s draft water strategy
14 New homes are only a small fraction of the
housing stock and there is huge scope for
Londoners to make improvements to their
existing homes. The homes that are with us
today represent roughly two thirds of the
homes that will still be with us in 2050. These
can be made more water efficient by either
adapting existing appliances or installing new
more efficient ones. The Mayor supports the
objective, set out in Future Water, of reducing
overall domestic consumption to 130 litres
per person per day by 2030. The Mayor
welcomes the Bathroom Manufacturers
Association’s recent introduction of a
voluntary labelling scheme for water efficient
bathroom products, but this is just one of
several labelling systems. The Mayor would
support the introduction of a single national
scheme, with a water efficiency ranking
system that is clear for consumers.
15 Water use accounts for 27 per cent
of carbon emissions from the home –
18 per cent from the heating of water for
baths, showers, and hand washing and
washing up, and nine per cent from waterusing
appliances such as washing machines.
Reducing water use, whether by taking a
shower rather than a bath or replacing an
old dishwasher with a more efficient one,
will reduce household carbon emissions. It
will also reduce the household energy bills
and help to offset the likely water price
increases (see paragraph 30).
Proposal 5 The Mayor has announced a
commitment to improve the energy efficiency
of London homes. This strategy highlights
the need for existing homes to become more
water efficient. Improving energy and water
efficiency at the same time is both sensible
and the least cost way of helping Londoners
to control their energy and water bills as well
as to reduce their greenhouse gas emissions
Proposal 6 The Mayor will work with the
water companies, the Environment Agency,
and other partners in joint programmes to
raise awareness of the benefits of water
efficiency, including the possible savings that
householders can achieve through their water
and energy bills.
16 Our drinking water is amongst the best in
the world but, even so, we buy vast amounts
of bottled water. Tap water is roughly 1,000
times cheaper than bottled water and the
carbon footprint can be up to 300 times
lower, for example, than with some imported
brands. In February 2008 the Mayor and
Thames Water launched the London on
Tap campaign to promote tap water in
restaurants, cafes and pub. Last December,
the Mayor announced the winner of a
competition to design a carafe to be used to
serve tap water throughout the capital.

Proposal 7 The Mayor will work with the
water companies and other partners to raise
awareness of the high quality of London’s tap
water, the contribution of bottled water to
climate change, and the benefits of drinking
water to health and wellbeing. He will also
encourage restaurants, bars and hotels across
London to serve tap water to customers.
Chapter 4 – Managing rainwater
17 Rainwater is either lost through evaporation,
seeps into the ground to replenish
groundwater levels, flows over the ground
and returns to streams and rivers or enters the
drainage systems. Using rainwater before it
goes down the drain can help to relieve the
pressures on the drainage system, so reducing
flood risk and the demand for fresh water.
18 Instead of using water from the mains,
householders could use rainwater for garden
watering from a rainwater butt. With a more
elaborate rainwater harvesting system, it can
also be used for toilet flushing and clothes
washing. Greywater – the wastewater from
hand washing, baths and showers, and
clothes washers – can also be used for toilet
flushing and outdoor water use with an
appropriate water reclamation system.
19 Conventional drainage systems, with pipes
and sewers, are designed to take surface
water away from streets and buildings as
quickly as possible and discharge it into the
main sewers and watercourses. Sustainable
drainage systems (SUDS) seek to mimic
natural drainage, managing more water
above-ground, close to the source, in order
to reduce the volume and speed of waters
flowing into sewers after storms.
Proposal 8 The Mayor will encourage green
roofs, rainwater harvesting, grey water
recycling and sustainable drainage through
planning policies in his new London Plan.
20 Surface water flooding can result from
prolonged periods of rainfall, when the
ground is already waterlogged, or during very
heavy storms when the rainwater overwhelms
the drainage system. Because so much of
London’s surface is concrete and tarmac, and
therefore impermeable, we are very reliant
upon our drainage system to keep us dry.
21 Responsibility for drainage currently rests
with many agencies, including Thames Water,
the London boroughs (for land drainage
and the local road network), Transport for
London and the Highways Agency (for their
road networks) and private landowners.
No one agency is responsible for reporting
or recording surface water flooding. This
confusion over responsibilities led the Mayor
to establish the Drain London Forum as a
partnership to facilitate coordinated action.
Proposal 9 The Mayor will work with partners
through the Drain London Forum to create
a strategic-level surface water management
plan for London by 2012. This plan will assist
boroughs in producing their Surface Water
Management Plans, will prioritise strategic
actions and enable a regional submission for
government funding to manage surface water
flood risks in London.
11

12 The Mayor’s draft water strategy
Chapter 5 – Disposal of wastewater
in London
22 In the mid-1800s, Sir Joseph Bazalgette
designed and built London’s combined
sewers. Still in use today, these remove
wastewater and rainwater in the same
pipe from properties in central London. In
order to avoid the flooding of streets and
properties with sewage during heavy rainfall,
Bazalgette provided overflows into the tidal
River Thames and its tributaries (together
referred to as the Thames Tideway).
There are now 57 such outlets, known as
Combined Sewer Overflows or CSOs, which
allow rainwater and diluted sewage to spill
untreated into the Thames Tideway after
intense rainstorms.
23 Discharges occur at some CSOs between
50 to 60 times each year. Widespread heavy
rainfall can lead to over a million tonnes of
untreated sewage and rainwater spilling into
the rivers. Despite much improvement in
the general quality of Thames river water,
the overflows are clearly unacceptable
in the 21st century, and contravenes the
Urban Waste Water Treatment Directive that
requires wastewater to be treated before it is
discharged.
24 Two tunnels are proposed to collect these
discharges and take the wastewater for
treatment at Beckton in east London. The
Thames Tunnel will intercept the CSOs along
the Thames from west London to Beckton.
However, the first phase of work will be
the construction of the Lee Tunnel from
Abbey Mills to Beckton and the upgrading
of Beckton sewage treatment works. This
will deal with discharges from Abbey Mills
that accounts for up to half the discharges
from the CSOs along the Tideway. This is
scheduled for completion in 2014, with the
Thames Tunnel completed in 2020.
Proposal 10 The Mayor will work with Thames
Water and other partners to support the
construction of the Thames and Lee Tunnels,
in a cost-effective way and minimising
disruption, as a means of greatly reducing
storm discharges from the combined sewer
system and improving the quality of the water
in the River Thames.
25 In many cases the pollution in London’s
rivers comes from sewer misconnections.
If a householder, or professional plumber,
deliberately or inadvertently but illegally
connects household appliances to the
surface water drain instead of the foul
sewer, then foul water can find its way into
streams, rivers and canals without any prior
treatment. Thames Water estimates that
one in every 20 houses in London has a
misconnection, and in some areas the figure
is considerably higher.
Proposal 11 The Royal Institution of Chartered
Surveyors should consider including a survey
of sewer misconnections as part of the
surveys at the time of sale of a property.
26 Fat, oil and grease (FOG) contribute
significantly to blockages in sewer systems
and these often result in flooding of
properties and pollution. Restaurants,

takeaways and other cooked food
establishments are the source of most
problems. There is a long-established
infrastructure in the UK for the collection
of used cooking oil (UCO) that can then
be converted into biodiesel and sold as
a transport fuel. As a direct replacement
for diesel fuel, it meets the government’s
Renewable Transport Fuel Obligation’s
sustainability and environmental criteria and
avoids the problems of FOG.
27 Sewage treatment can be another source of
energy. Mogden, Long Reach, Deephams,
Hogsmill and Beddington sewage treatment
work generate electricity by using sewage
gas. There is the potential to increase the
amount of electricity generated and to export
this to the public supply network. Utilising
sewage gas, which is mainly methane, in
this way reduces the release of this powerful
greenhouse gas to the atmosphere.
Proposal 12 The Mayor will work with Thames
Water and other partners to identify ways in
which the management of sewage can provide
renewable energy and reduce emissions of
greenhouse gases. The Mayor encourages
Thames Water and other partners to identify
opportunities to use new technologies to
contribute towards the Mayor’s targets for
decentralised energy, particularly through the
production of biogas, and greenhouse gas
emissions reduction.
Chapter 6 – Paying for water services
28 Understanding the history of the water
industry is important to understanding why
we pay for water in the way that we do.
There was much debate in 19th century
London over whether water should be paid
for through the rates as a public service or
should be metered and paid for according
to use. Eventually, the arguments favouring
a public service won. The majority of
Londoners still pay for their water and
sewerage services on the basis of the
rateable value of the property.
29 Ofwat sets price limits for each company
that allow the companies to finance their
functions. The current price limits were set
in 2004 (referred to as Periodic Review 2004
or PR04) for the period covering 2005-2010.
The next set of price limits, referred to as
PR09, will be set later this year to cover the
period 2010-2015. The government’s role is
to provide the national context of policies
and priorities for the water industry.
30 Thames Water has sought an increase in
customer bills of 17.2 per cent between
2009/10 and 2014/15. Over a quarter of
this increase is accounted for by expenditure
on the Tideway Tunnel. However, in its
draft response to water company plans,
Ofwat has proposed that there should be no
change to Thames Water’s average bills. Cost
increases should be avoided unless they are
truly necessary at all times, and particularly
during a recession. Nevertheless, the Mayor
considers this scheme as necessary to deal
13

14 The Mayor’s draft water strategy
with pollution caused by the CSOs along the
River Thames and in the lower River Lee.
31 Whilst there is evidence to support the view
that water metering leads to a reduction in
water consumption, there is also concern
that water metering could impose an
additional financial burden on some lowincome
households. The Mayor and the
Environment Agency therefore jointly
commissioned a study of the likely social
effects of the widespread introduction of
domestic water metering which suggests
that:
• Some households will pay more and
some less for their water, but for most
households the change will be less than
£20 per annum.
• Half the households with the lowest
ten per cent of income already spend more
than three per cent of their household
income on water, and the proportion
is likely to increase slightly as metering
becomes more widespread.
• Effects on costs will vary in different parts
of London because of differences in the
types of housing, sizes of households and
levels of income.
• A tariff that relates the metered water
charge to the Council Tax band of the
property is likely to provide the greatest
protection to low income households.
32 Although not part of this study, another way
of protecting vulnerable households affected
by the widespread introduction of water
meters is to help them to reduce their water
use through efficiency measures. The report
is being published concurrently with this
strategy. The results will be submitted to the
independent review of water metering and
charging being undertaken by Anna Walker,
which was announced by the government in
its water strategy Future Water.
33 Proposal 3 above stresses the importance of
tariff arrangements that protect vulnerable
and low-income households as part of the
programme for introducing water meters
throughout London

1 Introduction
1.1 Most people in London expect to turn on
the tap and get water without having to
think about where it comes from. Equally,
people want to be able to pull out the plug
and let water run away without having to
worry about what happens to it afterwards.
However, changes are going on around us
that mean that Londoners will have to pay
more attention to where water comes from
and goes to.
1.2 London is a dynamic, growing city and,
like other world cities, is facing the effects
of a changing climate along with growing
demands on resources. Together these
pressures will aggravate the stress on
existing systems by creating:
• greater demands for water from the
mains and, therefore, from the natural
environment
• increased flows to, and discharges from,
the sewage treatment works
• greater risks of surface flooding as
rainwater runs off new houses, driveways
and roads
• increased risks of storms and tidal surges.
• All in all, this means that we will have to
plan much more carefully how we provide
and use our water.
1.3 This strategy is intended to complement the
plans and strategies of other organisations,
including the government’s Water Strategy
for England published in February 2008
(see paragraph 1.5 below) by presenting a
London-specific view of water management.
It draws on the policies, strategies and plans
of others but also seeks to influence their
future development. Its purpose is to promote
improved water management – both in
terms of the water we want (such as drinking
water) and the water we don’t want (such as
sewage and floodwater in the wrong place).
This strategy considers all aspects of water
management and how they interact.
Arrangement of this document
1.4 This chapter gives a general explanation
of the context within which this strategy
is being prepared. The next two chapters
are concerned with the supply of water for
use in homes and businesses. Chapter 2
explains where our water comes from, and
the balance between supply and demand,
whilst Chapter 3 focuses on our use of
water and how we might use the water
that we have more effectively. After that,
attention shifts to how to manage the
water that we no longer need. Chapter
4 is concerned with rainwater and other
surface water whilst Chapter 5 is concerned
with wastewater collection, treatment
and disposal. Chapter 6 explains how
water services are paid for. Each chapter
begins with a policy setting out a water
management hierarchy, and includes
specific proposals for action.
Integrated water management
1.5 Future Water, the government’s Water
Strategy for England 1 , puts forward a vision
for water policy and management in which,
by 2030 at the latest, we have:
• improved the quality of our water
environment and the ecology which it
supports, and continued to provide high

16 The Mayor’s draft water strategy
levels of drinking water quality from our
taps
• sustainably managed risks from flooding
and coastal erosion, with greater
understanding and more effective
management of surface water
• ensured a sustainable use of water
resources, and implemented fair, affordable
and cost-reflective water charges
• cut greenhouse gas emissions
• embedded continuous adaptation to
climate change and other pressures across
the water industry and water users.
Figure 1.1 Water company service areas
1.6 The integration of water management as
a whole is central to the success of this
strategy. The government has recognised the
importance of taking an integrated approach
to water management in various recent
initiatives, such as the Water Act 2003 and
Future Water, along with other strategies
mentioned elsewhere in this document. The
Global Water Partnership (a partnership
between governments, water suppliers
and others) defines integrated water
resources management as a, ‘Process which
promotes the coordinated development

and management of water, land and
related resources in order to maximise the
resultant economic and social welfare in an
equitable manner without compromising the
sustainability of vital ecosystems.’
Governance of water
1.7 The roles of the various organisations
involved in the governance of water are,
in summary:
Water companies – four water companies
serve London (see Table 1.1 and Figure 1.1).
Regulators – these include:
• Environment Agency, which is the
environmental regulator of the water
industry. It has a statutory duty to manage
water resources. It does this by regulating
the volume of water that water companies
and other abstractors can take from the
water environment. It also reviews water
company water resource management
plans to make sure that there is enough
water for people, with an improved water
environment. The Environment Agency is
also responsible for water quality in the
principal rivers, streams, canals and lakes
and sets the standards for any discharges
into them. It is also responsible for
managing flood risk and minimising the
impact of floods.
• Water Services Regulation Authority
(Ofwat), which is the economic regulator
of the water industry. The primary duties
of Ofwat are to protect the interests
of customers by promoting effective
competition, and ensuring that the
Table 1.1 Water companies operating in London
Company Service
Thames Water Water supply and sewerage
Veolia Water Three Valleys Water supply only *
Essex & Suffolk Water (part Water supply only *
of Northumbrian Water)
Sutton & East Surrey Water Water supply only *
*Thames Water provides sewerage services in these areas.
purposes of each company are properly
carried out and that they are able to finance
their functions, in particular by securing a
reasonable rate of return on their capital.
• Drinking Water Inspectorate, which is
responsible for maintaining drinking water
quality. It checks that water companies
comply with their duty to supply wholesome
water and other regulations. These checks
entail audits of water companies’ samples
and tests as well as site visits, and the
Chief Drinking Water Inspector reports the
annually. The inspectorate also investigates
complaints and incidents related to drinking
water quality.
Consumer Council for Water (CCWater)
represents consumer interests in England
and Wales. CCWater is a non-departmental
public body, independent of regulators,
unlike its predecessor WaterVoice that was
part of Ofwat. Its functions are to:
• acquire and review as well as to publish
information about consumer matters
• advise and inform public authorities on the
views of consumers
• provide information to consumers
• monitor and challenges regulators as well
as water companies.
17

18 The Mayor’s draft water strategy
The Department for Environment, Food
and Rural Affairs (Defra) has overall policy
responsibility for water including water
resources; water quality (including drinking
water); water conservation; flood and coastal
defence; inland waterways; and the water
industry. It sets the regime within which the
water companies and the regulatory bodies
operate. It is the sponsoring department
for the Environment Agency, Ofwat and
the Drinking Water Inspectorate. The
department is also responsible for signing
off the River Basin Management Plans
referred to in paragraph 1.9 below.
European Union, which has adopted a
number of water-related Directives. In
particular the Water Framework Directive 2
is designed to protect and improve the
environmental condition of all waters. It
applies to surface waters (including lakes,
streams and rivers), groundwater, estuaries
and coastal waters (out to one nautical
mile). Its overall objective is consistent water
management across Europe in order to:
• reduce pollution, prevent deterioration
and improve the condition of aquatic
ecosystems including wetlands
• promote the sustainable use of water
• help reduce the effects of floods and
droughts.
Links with other plans and strategies
Water industry plans
1.8 It is now a statutory duty for water
companies of England and Wales to
prepare, consult, publish and maintain a
water resources management plan under
new sections of the Water Industry Act
1991, brought in by the Water Act 2003.
These plans detail how companies intend
to meet their customers’ need for water
over the next 25 years while protecting
and enhancing the environment. They
are reviewed annually and revised every
five years. In addition to water resource
management plans, water companies also
have drought plans which set out the
range and sequence of actions companies
would plan to take under various drought
conditions. More on these plans can be
found in paragraph 2.13 and 2.14. Every
five years, the water companies also
prepare business plans for approval by
Ofwat (see paragraphs 6.7 to 6.12).
River Basin Management Plans
1.9 Under the EU Water Framework Directive
all inland, estuarial and coastal waters must
aim to achieve ‘good ecological status’ by
2015, but more than 80 per cent of water
bodies in England and Wales currently fail to
reach this status. All river catchments (rivers,
streams, lakes and the land that drains
into them) are assigned to administrative
River Basin Districts. Also water-dependent
Protected Areas designated under other EU
Directives such as the Habitats Directive.
The River Basin Management Plans, now
being drawn up by the Environment Agency,
will set out environmental objectives and
programmes of measures to meet them for
all water bodies within River Basin Districts.

Mayoral strategies
1.10 The Mayor is responsible for strategic
planning in London. Among his wide range
of powers and duties, the Mayor must
prepare a Spatial Development Strategy
for London, known as the London Plan 3 .
This:
• is the strategic plan that sets out
an integrated social, economic and
environmental framework for the future
development of London, looking forward
15-20 years
• integrates the physical and geographic
dimensions of the Mayor’s other strategies,
and includes broad locations for change
and provides a framework for land use
management and development, which
is strongly linked to improvements in
infrastructure, especially transport
• provides the Londonwide context within
which the London boroughs must set their
local planning policies
• sets the policy framework for the Mayor’s
involvement in major planning decisions in
London
• sets out proposals for implementation
and funding
• is London’s response to European guidance
on spatial planning and is a link to
European Structural Funds.
1.11 Following public consultation and an
Examination in Public (EIP), the London
Plan was published in February 2004.
Since then, a number of amendments have
been made. A consolidated version of the
London Plan including all the alterations was
published in February 2008 4 . The London
boroughs’ development plans must be in
‘general conformity’ with the London Plan.
Whilst the London Plan continues as the
statutory Spatial Development Strategy for
London, the Mayor published A new plan for
London 5 in April 2009 outlining his proposals
for a new London Plan.
1.12 The Mayor is required under the Greater
London Authority Act 1999, as amended by
the 2007 Act, to prepare a Climate Change
Mitigation and Energy Strategy as well as
a Climate Change Adaptation Strategy for
London. Work in preparing the Adaptation
Strategy has identified the increased risks
faced by London of floods, droughts and
high temperatures. These predicted effects
emphasise the need to manage water
resources wisely as the amount of water
available decreases with increasing demand
(see paragraphs 2.37 to 2.39). The Water
Strategy covering surface water and drainage
related flooding manages the overlap on
droughts and flooding, with the Adaptation
Strategy covering tidal and fluvial flooding.
A first draft of the Climate Change
Adaptation Strategy was published in August
2008 6 , and a public consultation draft is due
to follow in the summer of 2009.
1.13 Other strategies prepared by the Mayor,
which have an influence on water, include:
• Municipal waste – litter and fly tipping can
be a serious problem, leading to blocked
drains and flooding. In the future there
may be opportunities for combining the
treatment of solid municipal wastes and
liquid sewage wastes.
19

20 The Mayor’s draft water strategy
• The London Housing Strategy 7 was
published in May 2009. It includes
objectives for more sustainable homes
including reduced energy and water
consumption and adapting to climate
change.
• Energy – The Climate Change Mitigation
and Energy Strategy, referred to above, is
now being drawn up. The treatment and
supply of fresh water and the treatment
of sewage are significant users of energy
and sources of greenhouse gas emissions.
However, the largest use of energy is to
heat water in the home.
• The Transport Strategy Statement of
Intent 8 , published in May 2009, forms a
framework for developing the new strategy
and contains potential policies and
proposals that could be developed further,
setting the scene for a full draft of the
strategy that will be consulted on in the
autumn of 2009.
• Rising to the Challenge: Proposals for
the Mayor’s Economic Development
Strategy for Greater London was
published in May 2009. It sets out the
Mayor’s broad intentions for building
London’s economic future.
• Biodiversity strategy – The Biodiversity
Strategy for London was published in
2002. It recognises the importance of
the Thames and other waterways for
biodiversity, and promotes the restoration
of de-graded tributary rivers.
Investing in infrastructure
1.14 In 1985 the then Greater London Council
said in a report London’s Decaying
Infrastructure: The Way Ahead 9 that ‘by
many standards London now [1985]
compares badly with other major European
cities in terms of the quality of life for its
residents and workers, and in terms of
its attraction as a location for investment
and growth ... there is no doubt that the
decline of much of London’s infrastructure
(particularly in Inner London) reinforces
these problems’. It went on to say:
• In 1985, ‘most of London’s central sewer
system [was] more than 70 years old, and
almost half the water mains [were] over 75
years; a substantial proportion [was] over
100 years old’
• Local authorities, House of Lords’
committees and the government had
all expressed concern about the failure
rates of water mains and sewer piping.
The estimates of the level of necessary
maintenance and renewal differed widely
• The government’s financing limits were
reducing capital spending programmes.
1.15 There has been major investment, for
example in the London Ring Main, for
water supply. However, in many ways,
24 years after this report, the statistics
have just moved on with half the water
mains now over 100 years old. It is only
relatively recently that Thames Water has
been able to begin a major programme to
replace the Victorian mains. It expects to
have replaced 2048 kilometres of mains,
or nearly seven per cent, by 2010. Current
consumers have to bear the cost of past
underinvestment in maintenance.

1.16 The combined sewerage network, built
under the direction of Sir Joseph Bazalgette
in the 1860s, is still carrying out its original
dual function effectively; namely to convey
London’s sewage to the major sewage
treatment works and to act as a surface
water drainage system. However, whilst
standards in sewage treatment in general
have improved greatly, the direct pollution
of the River Thames from these overflows
is no longer acceptable in the 21st century.
Dismantling the 19th century combined
sewer and replacing it with two separate
ones would be prohibitively expensive.
Instead there are other options to make the
combined sewer system more sustainable
(see paragraph 5.3).
Towards sustainable development
1.17 The government published its strategy
for sustainable development Securing the
future, in March 2005. The goal is to ‘enable
all people throughout the world to satisfy
their basic needs and enjoy a better quality
of life, without compromising the quality of
life for future generations.’ There are four
‘priority areas’ for immediate action:
• Sustainable consumption and
production. This is about achieving
more with less. It not only looks at the
production of goods and services, but
also at the effects of products across their
whole lifecycle.
• Climate change and energy. Average
global temperatures as well as sea levels
are rising. Ice and snow cover is declining.
Scientific evidence points to human
activity as being the primary cause of
these changes.
• Natural resource protection and
environmental enhancement. Natural
resources are vital to our existence. There
is a need for a better understanding of
the environmental limits and the practical
potential for habitat restoration and
21

22 The Mayor’s draft water strategy
enhancement where the environment is
most degraded.
• Sustainable communities. Sustainable
communities should embody the
principles of sustainable development at
the local level.
1.18 One of the primary reasons for preparing this
Water Strategy is to move towards greater
sustainability in London. The government
has charged the Environment Agency,
and more recently Ofwat and Consumer
Council for Water, with a duty to promote
sustainable development. One part of this
is about achieving more with less. In doing
so, it is wider than just the infrastructure
and the provision of water services; it is also
about people’s attitudes and behaviours.
As the demand for water rises across the
whole of the south east of England (see
paragraphs 2.7), London can no longer rely
solely on drawing in ever more water from
the surrounding counties as its population
grows. London must start to use the water
that it already has more effectively.
1.19 There is a perception that ‘efficient water
use’ is synonymous with ‘a poorer service’.
This is a myth. For instance, a toilet flush
volume of four and a half litres can provide
the same performance as a flush volume of
seven litres. Dual-flush toilets are common
in many countries but are still unusual in
the UK. Similarly the use of reclaimed water
(such as rainwater or grey water) for nonpotable
needs improves water efficiency
as well as helps to lessen the load on the
drainage infrastructure.
1.20 Clear objectives and targets should support
each step towards sustainable development.
The Mayor wants to ensure that over the
years to 2031, London excels among global
cities – expanding opportunities for all
its people and enterprises, achieving the
highest environmental standards and quality
of life and leading the world in its approach
to tackling the urban challenges of the 21st
century. The following three key objectives
and principles for water management in
London are therefore proposed as the basis
for translating this vision into specific actions
in the later chapters of this strategy.
Objectives
• To use the water London already has
more effectively and efficiently. The
majority of London’s water supplies come
from the rivers Thames and Lee upstream
of the tidal reaches, and it is unrealistic
to view London in isolation from the
upstream freshwater catchments. As the
demand for water rises across the whole
Thames basin, London can no longer just
rely on drawing in ever more water to meet
their needs. Instead, it needs to use the
water that it already has more effectively
and efficiently, reducing leakage, reducing
demand for water and simultaneously
reducing carbon emissions.
• To minimise the release of untreated
wastewater and diffuse pollution into
the water environment. Untreated
wastewater can find its way into London’s
rivers and watercourses via the drainage
system. The design of the combined sewer
system and sewage treatment works allow

this under storm conditions in order to
prevent flooding. Incorrectly connected
drains add to the pollution of rivers and
canals. Rainwater runoff in an increasingly
paved London carries yet more pollutants
– so called ‘diffuse’ pollution because
it has no singe source – into ponds,
lakes and streams. All these have serious
consequences for health, biodiversity,
tourism and the overall quality of life.
• To reduce the threat to people and
their property, businesses and essential
infrastructure from sewer, groundwater
and surface water flooding and to
mitigate its effects. As the climate
changes, London needs to maintain and
improve its resilience against river and
tidal flooding – to be covered more fully
in the Mayor’s Climate Change Adaptation
Strategy. However, all too often other
sources of flooding – from surface water
(as experienced in the summer of 2007),
groundwater and sewers – are overlooked.
These problems are also likely to get worse
as a result of climate change. Proper
attention being given to the nature of the
site in terms of site layout and building
design, and properly integrated, designed
and managed drainage and sewage systems
are all essential to alleviating these types
of flooding.
Principles
• Delivering practical changes locally.
There are many ways in which London
can use the water that it already has more
effectively. We need to reduce our water
consumption before looking beyond
London for new resources.
• Maintaining London’s infrastructure
for future generations. London now has
to bear the cost of past failures to maintain
and renew its infrastructure. We have to
bear these cost rather than pass an even
larger burden on to future generations
• Promoting consumer awareness and
help consumers to avoid unnecessary
consumption. There are many
opportunities, and a need, to educate
Londoners about where their water comes
from, how we can use the water that
we already have more effectively and
efficiently, and how we can all benefit
from doing so.
• Working together. Organisations should
work together to avoid duplication,
minimise conflicts and achieve better
results.
Implementation and monitoring
1.21 The majority of the actions proposed or
referred to in this strategy are being or will
be implemented by organisations other than
the Mayor of London. The role of the Mayor
is to set out his vision of how Londoners
will best be served, and to work with the
organisations responsible for providing
or regulating the services to achieve the
optimum outcome.
1.22 This strategy does not propose any
additional monitoring arrangements. The
returns submitted by every water company
to Ofwat in June each year, known as
the June Returns, provide a mass of data
23

24 The Mayor’s draft water strategy
that is then made available on the Ofwat
website. This, for example, is the source
of the information provided in Table 2.7
Water supply statistics for London. The
environmental performance of the water
companies is monitored by the Environment
Agency that publishes a wide range of
information on, for example, water resources
and river pollution incidents. Last, but not
least, the Mayor is required to publish a
State of the Environment Report for London
every four years.
Next steps
The publication of this draft starts a three
month period of consultation with the public
and other stakeholders, during which the Mayor
would like to receive your views about the issues
raised in the strategy. Consultation ends on 27
November 2009.
Please send your comments
by email to water@london.gov.uk
or by post to :
Draft London Water Strategy
Post point 19
City Hall
The Queen’s Walk
London SE1 2AA

2 Pressure on water resources
Introduction
2.1 Water is essential. We drink it. We use it in
our homes and gardens, in commerce and
industry. Over the years, Londoners have
become accustomed to having as much
high quality water as they want, when they
want it.
Where we get our water
2.2 The Thames basin is the largest river basin in
the south east of England. As such, it offers
a more dependable supply of water during
droughts than other catchments in the south
east of England because it is able to collect
Figure 2.1 Regional water sources
more water. In particular, London benefits
from its location on the lower stretch of the
river Thames. By the time the River Thames
reaches London, the flow has gained from
many smaller rivers and streams and as well
as from groundwater. The Chalk, Greensand
and Oolite aquifers of the Thames catchment,
shown in Figure 2.1, are important sources
of water for the communities in those areas
but they also provide the ‘baseflow’ into the
tributaries of the River Thames. They help
sustain river flows during dry summer months.
London water sources are shown in more
detail on Figure 2.3.
Teddington Weir is the point at which the freshwater River Thames flows into the tidal River Thames
Source: Environment Agency

26 The Mayor’s draft water strategy
2.3 London’s annual rainfall is surprisingly
low when compared to other capital cities
(see Table 2.1) and the rest of England
and Wales. Combined with the large
population, this means that the amounts
of water available per person is less than in
many hotter and drier Mediterranean and
African countries. As a reference point the
World Bank considers any country with less
water availability than 1,000 m 3 /person/
year to be ‘water scarce’. However, the
rainfall is fairly uniform throughout the year
and evaporation is modest. London also
benefits from the contribution of a slightly
higher average rainfall in the River Thames
catchment as a whole to both the flow in the
Thames and recharging the aquifers.
2.4 Of the rain that falls in the Thames
catchment, two thirds is either lost to
evaporation or used by growing plants
(transpiration). Of the water that is then
Figure 2.2 What happens to rainfall in the Thames catchment
100
90
80
70
60
50
40
30
20
10
0
Evaporation
and used by
growing plants
Required to protect
the natural environment
Effective
rainfall Water available
for supply
Table 2.1 Average city rainfall comparisons
City Rainfall (mm/year)
London 590
Jerusalem 597
Istanbul 629
Mexico city 662
Edinburgh 664
Thames Region 690
Newcastle 700
Dublin 740
Rome 791
Manchester 809
England and Wales 897
Sydney 1,226
Source: City rainfall data compiled by Waterwise from
relevant country MET office websites.
‘available’, 55 per cent is abstracted for use,
one of the highest amounts in the country 10 .
All the available water cannot be taken
because some must be left to protect the
Use in agriculture,
industry and for
other purposes
Public supply
Use by business,
hospitals, hotels, schools,
and for other purposes
Household use
Rainfall Effective rainfall Water available Public supply

Figure 2.3 London water sources
27

28 The Mayor’s draft water strategy
natural environment including fish, river
and riverside plants and water birds. Of
all the water abstracted, 82 per cent is for
public supply and of this half is supplied to
households and a quarter to non-households
(the remainder being lost through leakage).
This sequence is shown diagrammatically in
Figure 2.2.
2.5 The majority of London’s water supplies
come from the rivers Thames and Lee, with
about 80 per cent of all the water taken
from the freshwater River Thames upstream
of Teddington Weir. It is then stored in
reservoirs around the capital. The remainder
is abstracted from the ‘confined chalk’,
which is concealed below the clay of the
London basin, shown by the grey shaded
area on Figure 2.1. The various sources are
shown in more detail on Figure 2.3.
2.6 In 2006, Defra asked the Environment
Agency to advise on which areas of the
country it considered to be seriously water
stressed. The agency looked at the areas
where household demand for water is a high
proportion of the rainfall that is available
to meet that demand, both now and in
the future. Following consultations, the
Environment Agency published its Areas of
water stress: final classification 11 at the end
of 2007. This report categorised London,
© Andrew Holt / Alamy

along with much of the South East, as an
area of ‘serious’ water stress.
Our growing demands
2.7 Following World War II, the policies of
decentralisation led to a steady drop
in London’s population until the mid-
1980s, as shown in Figure 2.4. Since
then, the population has steadily grown,
and is expected to rise from the present
7.56 million to between 8.79 and
9.11 million by 2031. The number of
households will grow faster than the overall
population as the average household size
is falling, due mainly to later marriage,
fewer children, more divorce and longer
lives. Of the 720,000 to 860,000 additional
households by 2026, three quarters will
be single person households. In order to
accommodate this growth, the current
London Plan sets a target of 30,500
additional homes per year. The growth in
London’s population means more water will
have to be supplied, more sewerage treated
Figure 2.4 London’s population 1911 – 2031
London population (millions) .
10
9
9
8
8
7
7
6
6
5
and sludge disposed of, and construction of
more homes for this growing population will
mean more surface water runoff.
2.8 Water use rose more or less continuously
during the twentieth century. The fall in
industrial demand for water has been more
than outpaced by the rise of household
use. Averaged over the past five years,
each Londoner uses 161 litres of water a
day compared to the national average of
150 litres per person per day. This headline
figure conceals many variations because
households:
• have different appliances and fittings (see
Table 2.2)
• have a different number of occupants at
different stages of life (see Table 2.4)
• have different attitudes to water use
• have a range of lifestyles that reflect in
their water use.
• In 2007/08 the area with the highest
average consumption within London were
un-metered households in Veolia Water
Actual population to 2008
High projection 2008 to 2031
Low projection 2008 to 2031
29

30 The Mayor’s draft water strategy
Three Valley’s Central water resource zone
at 181.6 litres and the lowest was metered
households in Sutton & East Surrey Water’s
East Surrey water resource zone at 137.7
litres per person per day.
2.9 Table 2.3 compares London’s individual water
use in 2004 with other western European
capitals 13 . London is shown as 100.
2.10 Water demand is not just about a growing
population. The number of occupants in a
household also influences individual water
use. Table 2.4 shows how individual water
use differs depending on the number of
people in a household in Thames Water’s
supply area. It shows that, in the context
of water use, the economies of scale favour
multiple occupancy households. This
conflicts with the trend towards smaller size
households in London.
2.11 Generally households with a meter use less
water than those without (see section 3.17).
Just over one in every five properties in
London has a water meter. This lags behind
much of the rest of the developed world
where metering is the norm. For instance
Australia, Austria, Denmark, Finland, France,
Germany, Japan and Switzerland already
have 100 per cent metering of single-family
houses 15 . As a result, companies providing
water to Londoners have limited data on
how much households are using in different
areas, and what factors influence that use.
Their ability to influence the household
use of water, and indeed their ability to
measure and manage their use, is low. It is
also in contrast to gas and electricity, where
householders have always paid for their use
by the volume used.
Balance of supply and demand
2.12 To avoid running out of water, or damaging
the environment by abstracting too much
water (for example, by reducing river flows
to a level where fish cannot survive), it is
essential to balance supply and demand.
During most years, including most summers
and dry periods, there is sufficient water
in the rivers Thames and Lee together with
groundwater to meet London’s needs.
However, during prolonged periods of low
rainfall, supplies are limited and drought
actions may be required. Typically it takes
two winters of below average rainfall to
necessitate drought actions. Winter rainfall
is particularly important because it is during
the winter that groundwater stores are filled
so that they can support river flows and
abstraction in the next spring and summer.
Water companies have both Water Resource
Management Plans for the long-term and
drought plans to manage supplies in times of
shortage.
2.13 Water Resources Management Plans set
out how each water company intends to
balance supply and demand, and how it
intends to provide sufficient water to meet
demand and protect the environment over
the next 25 years. Water companies update
their plans every five years, in line with the
price review process (see Chapter 6). Since
2007, these plans have been a statutory
requirement under the Water Act 2003,

Table 2.2 National average domestic water use
Range of household water use
Litres/person/day Percentage used
Household water use Fitting or appliance Low High Median Low High
Toilet use Toilet use 35 45 39 22% 31%
Personal washing Bath 21 35
Shower 6 20
Hand basin 10 15
51 32% 34%
Drinking water Drinking water 2 2 2 1% 2%
Clothes washing Washing machine 14 25
Sink 0.6 1.3
Dish washing Dishwasher 1 5
Kitchen sink 7 10
22 12% 13%
12 7% 8%
Car washing Car washing 0.9 1.2 1 1% 1%
Garden watering Sprinkler 0.3 4
Other means 4 10
9 3% 7%
Miscellaneous* Miscellaneous 13 32 20 11% 16%
Median water use, and high and low percentage variation 156 89% 112%
• The miscellaneous category includes filling swimming pools and ponds, as well as cooking, cleaning and watering
houseplants. Source: Environment Agency 12
Table 2.3 Water use in some European capitals
(2004)
City Relative water use
per person
Rome 192
Stockholm 143
Athens 113
Madrid 113
Amsterdam 106
London 100
Paris 96
Berlin
Source: BIPE
80
14
Table 2.4 Water consumption in households of
different sizes
Number of
occupants
Individual water
consumption
(litres/person/
day)
Reduction per
person compared
to a single person
household
Single
occupancy
household
207 0%
2 people 172 17%
3 people 148 29%
4 people 135 35%
5 people 131 37%
6 people 127 39%
Source: Thames Water
31

32 The Mayor’s draft water strategy
and the companies published their draft
plans for public consultation in May 2008.
After taking account of the consultation
responses, the companies submitted their
revised plans to Defra in April 2009, and in
August the Secretary of State announced
that he had called for an inquiry into Thames
Water’s draft Water Resource Management
Plan.
2.14 The Water Act 2003 also requires all water
companies to have sound Drought Plans in
place so that they can continue to supply
water to their customers when sources are
depleted. Table 2.5 highlights the different
actions that water companies can take to
conserve water resources during a drought.
2.15 In their Drought Plans, and their Water
Resource Management Plans, the water
companies specify the expected frequency
of using drought measures. The industry
commonly refers to this as a company’s
Table 2.5 Drought actions available to water companies
‘levels of service’. A supply-demand deficit
arises if a company has insufficient water
available to meet its customers’ reasonable
needs in a dry year. A dry year demand is
the utmost demand a company can meet
without having to introduce restrictions
at any time in the year, but there is no
set definition of what constitutes a ‘dry
year’. Table 2.6 details the levels of service
commitments for the four water companies
serving London set out in their five-year
business plans.
2.16 Studies carried out by Thames Water with its
customers suggest that they do not regard a
reduction in the frequency of hosepipe bans
as a priority (see paragraph 6.14).
2.17 Under current legislation (section 76 of the
Water Industry Act 1991) a water company
can temporarily ban or restrict the use of
hosepipes for watering private gardens or
washing private motor vehicles if, in its view,
Customer measures Engineering measures
Promote campaigns and water Use alternative or unused sources.
awareness.
Increase efforts to reduce leakage.
Introduce hosepipe and sprinkler bans. Introduce bulk transfers (eg large transfers of water between water companies).
Seek restrictions on non-essential uses Improve the distribution network.
(see paragraph 2.17).
Lower groundwater levels.
Seek rota cuts (eg restricting water
supplies to certain days or times or to a
much lower pressure) or standpipes (ie
pipes in the street from which people
have to collect water).
Seek additional sources of water.
Modify discharge regimes (eg suspend or modify an obligation to discharge
‘compensation water’ into a canal, river or stream).
Note: See water companies’ drought plans for details on how and when companies would apply these measures

there is or could be a serious shortage of
water for it to distribute to its customers.
When hosepipe bans were last introduced in
the summer of 2007, there were complaints
(including many letters to the Mayor) that
Table 2.6 Companies’ levels of service – water supply restrictions
public gardens were still being watered
and paving washed down. The government
now proposes to widen the range of
non-essential uses of water that can be
controlled by water companies. This would
Water Company Hosepipe ban Drought order/permit Rota cuts/standpipes
Thames Once every 20 years Once every 20 years Never
Veolia Water Three Valleys Once in 10 years Once in 20 years Unacceptable
Essex & Suffolk Once in 20 years Once in 50 years Never
Sutton & East Surrey Once in 10 years Once in 20 years Once in 100 years
Table 2.7 Water supply statistics for London (2008/09)
Population served (000)
(London per cent of company total)
Overall water supplied (million litres per day)
(London per cent of company total)
Thames Three
Valleys
6,090
(71.1%)
1,870
(72.7%)
1,015
(32.5%)
281
(34.1%)
Essex &
Suffolk
532
(29.8%)
136
(30.1%)
Sutton &
East Surrey
Total
289
(44.7%) 7,927
67
(43.5%) 2,354
Proportion of London’s water distributed by company 79.5% 11.9% 5.8% 2.8% 100%
Household water consumption (litres/person/day) 160 173 160 161 162
Proportion of households with water meters in
London
21.2% 33.5% 42.7% 28.2% 24.5%
Distribution loss (million litres per day)
378 35 14
7 435
Percentage loss
20.2% 12.4% 10.6% 10.1% 18.5%
(London per cent of company total)
(75.0%) (39.1%) (32.5%) (44.3%)
Total leakage (million litres per day)
527 52 22
11 611
Percentage loss
28.2% 18.5% 15.9% 16.4% 26.0%
(London per cent of company total)
(75.1%) (36.8%) (32.4%) (44.7%)
Leakage per property (litres per day) 207 127 94 88 185
Security of supply index 2008/09 56 100 84 100
Security of supply index 2007/08 89 100 100 82
Security of supply index 2006/07 60 100 100 97
The figures in brackets show the London proportion the company-wide totals. Security of supply index is a measure of
each company’s ability to supply customers in dry years without imposing demand restrictions such as hosepipe bans.
100 is the highest index score. The index relates to the whole company. Source: Water companies’ June Returns to Ofwat
33

34 The Mayor’s draft water strategy
increase the ability of water companies to
manage demand in times of water shortage,
particularly in the early stages of a drought
or where supplies of water available for
distribution deteriorate rapidly
2.18 Domestic uses that might be prohibited as a
result of these changes include, for example,
the cleaning of patios with a hosepipe or
pressure washer and the filling of domestic
swimming pools. The government also wants
to allow the water companies to use their
powers to ban or restrict nonessential uses
of water more flexibly. The government is
currently seeking views on these changes
through its consultation on the Draft Flood
and Water Management Bill 16 .
2.19 In general the Mayor supports these
proposals but they need to apply to public
areas as much as domestic use if they are to
gain the support of the general public.
2.20 Water companies divide their supply area
into ‘water resource zones’ (WRZ) that
are defined on the basis of good water
supply connectivity. Customers in each
zone experience the same risk of water
restrictions. There are six zones covering
London, which also supply water outside
London. The current dry year annual average
situation for these zones is:
• Sutton & East Surrey Water
- East Surrey WRZ: Critical peak deficit
until 2011/12. No dry year annual
average deficit
- Sutton WRZ: No deficit
• Essex & Suffolk Water
- Essex WRZ: Deficit until 2013/14
• Thames Water
- London WRZ: No deficit (assuming
the desalination plant is online – see
paragraphs 2.21 and 2.31)
• Three Valley Water
- Southern WRZ: No deficit
- Central WRZ: No deficit
2.21 In a dry year, Thames Water currently
forecasts that its demand for water in its
London resource zone would be about
80 million litres per day (Ml/d) greater than
its available supply. This is equivalent to
about half million people’s daily demand,
but it is a significant improvement on the
previous forecast of 170 Ml/d. This has
largely been achieved as a result of the
Victorian Mains Replacement Programme
(see paragraph 3.8) and other action to
reduce leakage. Even so, large parts of
London’s water supply network date back to
the Victorian period, with over 60 per cent
of the network built pre-1900. It is this
aged infrastructure that leads to most
parts of London having the highest levels
of mains leakage in England and Wales.
The desalination plant at Beckton (see
paragraph 2.31) that is undergoing its final
commissioning will close this deficit.
2.22 The security of supply index is an indicator
of the extent to which the company is able
to guarantee provision of its planned levels
of service. A company showing a supplydemand
deficit (or in other words having a
security of supply index of less than 100)
means that its customers face a higher risk

of water restrictions than that stated in the
company’s level of services (see Table 2.6).
Yet a deficit does not imply that restrictions
are inevitable in a dry year, as it is more of
an indicator of ‘theoretical risk’. However,
there will be a greater risk of restrictions
being imposed than if there were no deficit.
2.23 Table 2.7 summarises the companies’ water
supply statistics. The figures in brackets show
the London proportion of the company-wide
totals. The distribution loss is the volume of
water lost by a company through leaks in its
mains network. These losses together with
the leaks on the customers’ supply pipes add
up to the company’s total leakage. While
only 71 per cent of Thames Water’s domestic
customers live in London, 75 per cent of
Thames Water’s distribution losses occurred in
London. Alternatively, Thames Water supplies
79 per cent of London’s water but accounts
for 87 per cent of all distribution losses.
Proposal 1 The Mayor will work with the
water companies, the Environment Agency
and other partners in seeking the effective
management of London’s existing and future
water resources to meet the needs of the
growing population whilst protecting the
natural environment.
2.24 The Mayor has established a Water Resources
Working Group which brings together
representatives of the four water companies
serving London, the water industry regulators
(Environment Agency and Ofwat), central
and local government (Government Office
for London and London Councils), consumer
interests (Consumer Council for Water),
Waterwise, Transport for London and other
stakeholders. Its purpose is to coordinate
activities and improve the working relations,
including the flow of information, between
the various organisations. An example of
the issues addressed was London borough
councils’ concerns over water pressure
reductions (see paragraph 3.13 below).
Water efficiency
2.25 Since 1996, each water company in England
and Wales has had a duty to promote the
efficient use of water by its consumers. In
June 2008, Ofwat consulted on proposals for
setting water efficiency targets from 2010-
11 to 2014-15. Following that consultation,
Ofwat set targets for each water company
for 2010-2015 last November 17 , and the
companies are piloting these targets in
2009-10. The government said in Future
Water that it would consider whether some
form of water efficiency obligation on the
water industry was required in the light of
the experience of Ofwat’s targets.
2.26 In preparing the Draft Flood and Water
Management Bill 18 , the government
considered whether it should take the
opportunity to seek an enabling power
for the Secretary of State to place a water
efficiency commitment on water companies
in England, the level of which could be set
at a later date in the light of the success of
the current voluntary arrangements. It has
decided not to include such a clause in the
draft bill, pending any recommendations on
water efficiency that may be made by the
35

36 The Mayor’s draft water strategy
independent Walker Review of household
charging and metering for water and
sewerage services (see paragraph 6.22).
New resources
2.27 A discussion paper prepared in 2007 by
the Environment Agency Water for the
Future – Managing water resources in the
South East of England 19 concluded that by
2035 demand for water in the South East of
England would significantly outweigh supply
unless we reduce the amount of water we
use or find new resources. It notes ‘we can
build new resources, but we need to ask
ourselves how long we can go on doing this
and how resilient and flexible to climate
change these options will be looking forward
100 – 200 years. We need to try harder
to reduce the amount of water we use by
changing our behaviour, reducing waste and
making better use of new technologies’.
Limited scope for more abstraction
2.28 When a water company has or predicts larger
demands than the water supplies available
(a deficit) it looks at means to close the
gap by, for example, reducing leakage,
reducing demand (eg through metering)
as well as increasing supplies though new
abstractions. Water companies must have an
abstraction licence to take water from rivers
or aquifers. The Environment Agency decides
whether existing abstractions are causing
unacceptable harm to the environment,
such as reducing a river’s flow to an extent
that the fish stock cannot survive, or how
much more abstraction can take place. In
doing so, it prepares Catchment Abstraction
Management Strategies (CAMS) that assess
the status of local sources.
2.29 The three CAMS covering London are the
Thames Corridor CAMS, the London CAMS,
and the Roding, Beam and Ingrebourne
CAMS. The first of these shows that the
River Thames upstream of the weir at
Teddington is over-abstracted. The volume
of water taken out of the lower Thames can
account for as much as 50 per cent of the
natural flows in a normal summer, rising
as high as 80 per cent in droughts. Taking
any more water could increase the salinity
downstream of Teddington Weir, and that
would affect which species of fish can thrive
in the upper estuary.
2.30 The other two CAMS show that there are
very few opportunities in London, and indeed
across much of the Thames Region, to take
any more groundwater or surface water in
summer months. In many of the Thames’
freshwater tributaries, low river flows can
affect habitat and water quality and thereby
reduces diversity and number of fish. The
implementation of the Water Framework
Directive could lead to the Environment
Agency seeking reductions in the amount
of water taken from some London rivers in
order to achieve ‘good ecological status’. The
Water Framework Directive risk maps already
identify stretches of river at risk of failing.
Desalination
2.31 The largest deficit is in Thames Water’s
London resource zone. There is no single
option that could close the gap between

demand and supply in the short term. In
closing its gap, Thames Water aims to reduce
its overall leakage rate from 894 million litres
of water a day in 2005/06 to 685 million in
2009/10. At the same time, Thames Water
is constructing a new water treatment plant
at Beckton as a means of rapidly reducing its
security of supply deficit. The plant would
enable Thames Water to take water from the
Thames Estuary and remove the salt from
it. The plant will only operate when demand
cannot be met from conventional water
sources. At full operation, the plant could
supply 140 million litres of water a day;
enough water to supply 400,000 homes.
2.32 A biodiesel-fuelled electricity generation
plant is being built to offset the carbon
dioxide emissions. The plant is designed to
operate ‘24/7’ and the output will normally
be used to power the standard sewage
treatment processes at Beckton, with a small
amount going to the desalination plant to
keep it in a state of ‘preparedness’. The
generation plant will, over time, balance
the power requirement of the desalination
plant but it will not be able to meet the
peak power demand of 18 megawatts on the
occasions that it is in full operation.
A new reservoir
2.33 Some major new resource developments,
for example a reservoir, can take in excess
of 20 years from conception through to
implementation. Thames Water believes
that it will need a major new source of water
to meet the forecast demand by 2026. Its
preferred option is a new storage reservoir in
the Upper Thames area, outside of London.
Pumping water from the river Thames at
times of high river flows would fill the new
reservoir 20 . The reservoir, which is referred
to by Thames Water as the Upper Thames
Reservoir, has been included in the company’s
draft Water Resource Management Plan 21 .
However, the Environment Agency said in its
response to the draft plan that it is yet to be
satisfied that the proposed reservoir is the
best solution for the company’s customers,
the environment and the wider South East 22 .
In its Statement of Response to the public
consultation, Thames Water has said that the
scheme would be delayed up to five years and
may be reduced in size from 150 million cubic
metres (Mm 3 ) to 100 Mm 3 . As noted
in paragraph 2.13 above the Secretary of
State has now called for an inquiry into
Thames Water’s draft Water Resource
Management Plan.
2.34 The group opposed to the reservoir has
proposed alternatives, including water
transfer from the River Severn to the River
Thames and effluent reuse (see below).
The feasibility of Severn-Thames transfer
was studied by the former National Rivers
Authority in the early 1990s and at that
time it was considered to be a cost-effective
option for increasing water resources 23 .
However, it has not been supported by more
recent Environment Agency studies 24 or
considered feasible by Thames Water.
Wastewater effluent reuse
2.35 It is clear from what has been said above
that there is little scope for developing new
37

38 The Mayor’s draft water strategy
sources of river water or groundwater in
and around London. However, reclaiming
wastewater (referred to as ‘effluent
reuse’) from sewage treatment works is
a significant potential new resource that
Thames Water and other companies are
currently investigating. It would be a
dependable source but it may have an
‘image’ problem. Ensuring drinking water
integrity, understanding customer attitude,
and minimising the increased energy
consumption are the key associated issues.
2.36 What Thames Water is investigating is
indirect reuse, which is where the reclaimed
water would be returned to a watercourse
and then abstracted into storage to blend
with other water before treatment and
supply. This provides an important buffer
between the effluent discharge and the
water supply customer and mirrors what
happens elsewhere in the catchment.
However, the catchment areas of the London
works are heavily urbanized with significant
proportions of industrial effluents. This is
in marked contrast to the Langford Scheme
in Essex where the effluent is derived from
domestic customers. Thames Water believes
that it is right to complete its research
into the process requirements and risk
assessments before accepting that such a
scheme would be feasible.
The effects of climate change
2.37 In the longer term, water resources will be
affected by changes in our climate. The UK
Climate Impacts Programme have reported
that the UK is getting warmer by 0.4 – 0.9˚C
since 1914, whilst witnessing eight of the
ten warmest years on record since 1990. A
separate analysis of London’s climate record
has identified that summer temperatures
in London have risen at an average rate of
0.73˚C per decade over the last 30 years 25 .

2.38 In June 2009, the UK Climate Impacts
Programme published projections outlining
how the climate would change over the
coming century. The scenarios, know as
UKCP09, project climate changes according
to three greenhouse gas emissions scenarios.
The ‘medium emissions’ scenario, which is
closest to current international emission
levels, projects that by the middle of the
century London is likely to experience:
• an average 18 per cent decrease in summer
rainfall (see Figure 2.7) (but it is unlikely
to more than a 39 per cent decrease)
• an average 15 per cent increase in winter
rainfall (but it is unlikely to greater than
a 39 per cent increase) often becoming
heavier. The annual amount of rainfall does
not change
Figure 2.5 Change in London annual mean temperature (°C) Medium emissions scenario (50% probability level)
Figure 2.6 Change in London summer precipitation (%) Medium emissions scenario (50% probability level)
39

40 The Mayor’s draft water strategy
• summer mean temperatures may rise
on average by 2.7 degrees and winter
temperatures by 2.2 degrees
• summer cloud cover may decrease by up to
ten per cent.
2.39 These changes to the seasonality of rainfall,
increases in temperature and decreases in
summer cloud cover will have a dramatic
effect on the availability of, and demand
for water.
• Heavier rainfall can run off the ground
rapidly, limiting time that is needed for
water to slowly penetrate into the ground
and top up our groundwater.
• Drier summers will mean that waterways
will have low flows and be more sensitive
to any pollution.
• Increased frequency of extreme weather
including droughts could create a need for
new resources.
• Warmer winters will lengthen the growing
season, increasing the demand for water
from vegetation (whilst also reducing the
‘winter recharge period’ for our aquifers)
• Hotter summers will increase the amount
of water lost by evaporation.
• Increased subsidence and heave from
fluctuating soil moisture will lead to more
broken water mains.
• Heavier rainfall may overcome surface
water drainage networks, causing flooding.
Climate Change Act 2008
2.40 The Climate Change Act 2008 addresses
the issue of adaptation to the full range of
climate change risks. It introduces a power
for the Secretary of State to require public
bodies and statutory undertakers, including
water companies and the GLA, to carry out
their own risk assessments and make plans
to address those risks. The government
will be consulting on its strategy for using
this power later this year. In addition, the
government must report at least every
five years on the risks to the UK of climate
change, and publish a programme setting
out how these impacts will be addressed.
2.41 Water companies will be expected to use
the new projections to assess the impacts
of climate change on their Water Resource
Management Plans. Thames Water has
stated that it will undertake a sensitivity
analysis of the proposals in its Water
Resources Management Plan using the
UKCP09 information.

3 Managing water use
3.1 It is all too easy to take secure water supplies
for granted. Londoners rely on the water
companies to provide sufficient clean water
for their needs. In fact, each company has
a duty to provide homes with a supply of
water that is sufficient for household use.
3.2 The drought of 2006, with associated
widespread hosepipe bans and real risk of
more serious restrictions was a powerful
reminder to us all that our water resources
are not limitless. If it had lasted any longer,
it would have started to have quite serious
effects with restrictions on the use of water
for non-essential purposes. Yet, despite
water being so precious and scarce, we lose
vast volumes of water. In water-stressed
areas, it makes sense to place a greater
emphasis on managing water use. The Mayor
believes the current twin-track approach
of reduced demand and increased supplies
is right but must not be biased towards
increasing supplies. Although there may be a
need for new resources, the Mayor considers
that much more effort is needed to reduce
both leakage and our water demands,
benefiting both the water environment and
simultaneously reducing carbon emissions.
Policy 1 – Water use in London
The Mayor believes that we should apply
the following hierarchy for managing
water supply and demand in London:
1= Reduce the loss of water through
better leakage management
1= Improve the efficiency of water use
in residential, commercial and public
buildings (both new and existing)
3 Use reclaimed water for non-potable
uses (rainwater harvesting and grey
water recycling)
4 Develop, as necessary, those water
resources that have the least climate
change and environmental impact.
Leakage
3.3 Table 2.7 in the previous chapter showed
that a quarter of London’s water is lost
in distribution. Reducing leakage can
contribute to improving security of supply
in the same way as developing a new
source of water. Reducing leakage from the
distribution mains by one percentage point
(from 18.5 per cent to 17.5 per cent) would
provide enough water for 224,000 people.
This assumes that new housing is built to
Code of Sustainable Homes level 3 standard
with a water consumption of not more than
105 litres/person/day.
3.4 It is impossible to achieve zero leakage
from a large and complex network. All
utility networks (including gas, electricity
and water) suffer some losses from their
distribution systems. The water that is
lost still has to be paid for, and the losses
compound the need for further storage,
treatment and enlargement of water mains.
Thus, there is some tolerated level of
leakage. The government, regulators and
water companies accept an ‘economic level
of leakage’ (ELL) as the preferred tolerated
level of leakage. The economic level of
leakage is the point at which any further
effort to reduce leakage would not be costeffective;
or in other words, the point at

42 The Mayor’s draft water strategy
which it would cost more to reduce leakage
further than it would be to produce more
water from existing or alternative sources.
3.5 The procedure for calculating the ELL has
been revised and is now more sensitive
to costs and benefits including social and
environmental costs 26 . Ofwat now uses
the term ‘sustainable economic level of
leakage’ (SELL) to reflect this. Whilst there
is a good general understanding of the
social and environmental costs of action
to control leakage (for example, traffic
congestion due to mains replacement or
repair), the estimates of the environmental
benefits (such as reduced abstraction and
carbon emissions) are less clear. However,
in the London context, there are serious
omissions. For example, no account is taken
of the potentially serious damage caused
to other infrastructure such as the London
Underground network by leaks and burst
mains 27 . A recent study shows that there is
very little information available to assess
the costs of disruption and loss of business
caused by leaks and burst mains 28 .
3.6 The Environment Agency has identified
much of London’s water resources as ‘overabstracted’
(see paragraph 2.29), and the
Water Framework Directive will require
measures to address this. The Mayor
expects that the current price review will
take a longer-term sustainable approach
to London’s water infrastructure. There
is further discussion of ELL in Chapter 6
Paying for water.
3.7 Leakage has two elements; the volume of
water lost through leaks on the distribution
mains network (referred to as distribution
losses) and the amount lost from customers’
supply pipes (referred to as supply pipe
losses). In meeting their economic level of
leakage targets, water companies are:
• replacing old leaky distribution mains
• lowering the water pressure in the
distribution network
• finding and fixing leaks on their
distribution mains
• repairing leaks on their customers’ supply
pipes.
Replacing water mains
3.8 Many of London’s water mains are over 100
years old. But it is not just the age of the
pipes that leads to high leakage levels. The
soil can affect the pipes buried within it in
two ways: through corrosion (which causes
pitting and structural weakness) and through
movement of the soil that puts stress on the
pipes and their joints. Research shows that
London has a significantly higher proportion
of corrosive soils than other parts of the
country. Also, London’s clay soils are more
susceptible to soil movements due to the
changes in the soil moisture. Inner London,
served by Thames Water, generally suffers
the worst problems.
3.9 As part of the 2004 price review (see
Chapter 6 for an explanation of the price
review process) Ofwat set Thames Water
strict leakage reduction targets. In order
to meet these, the company embarked on
a major leakage reduction programme and

expects to have replaced 2,048 kilometres
(or nearly seven per cent) of its mains by
2010 as well as reducing the pressure in its
mains. To start with, Thames Water failed
to meet these Ofwat targets but has done
so since 2006-07. Between 2010 and 2015
the company plans to replace a further
2,097 kilometres of mains, including 600
kilometres of climate change investment.
However, under Ofwat’s draft response to
the company’s plans (see paragraph 6.12)
Thames Water would only be able to replace
1097 kilometres of mains.
3.10 In its Statement of Response to its draft
Water Resources Management Plan 29 ,
Thames Water has proposed a long-term
objective of reducing leakage in London
from the current (2008/09) figure of 209
litres per property per day to 114 litres in
2030-2035 30 . This is more ambitious than
the proposal in the draft Water Resources
Management Plan, which was to achieve
Case study | Leakage reduction in Tokyo and Hong Kong
Other world cities have made significant strides
in reducing their levels of leakage. For instance
the Bureau of Waterworks has reduced the
leakage rate in Tokyo to only 4.4 per cent
of the overall water demand for 2004 31 . The
Bureau has only achieved this through decades
of sustained action and expenditure. Between
1995 and 2004, Tokyo reduced the rate of
leakage from 9.3 per cent to 4.4 per cent.
Although it can be difficult to establish
the UK industry average of 141 litres per
property per day by 2020. There has been
under-investment in leakage control and
mains replacement for decades, and it
is accepted that it will take a long time
to achieve significant improvements.
Nevertheless, the Mayor considers that
Thames Water’s long-term aim should be to
achieve the best UK standard of 80 litres per
property per day.
3.11 Thames Water says, in its Statement of
Response, that reducing leakage below
what is currently proposed is an ‘extremely
expensive option because the amount
of leakage saved per kilometre of mains
replaced reduces significantly given that
the mains in our supply area in poor
condition with high levels of leakage and
bursts will have largely been renewed.’
However, the 25-year time scale of Water
Resources Management Plan should allow
for significant improvements to be achieved
whether such comparisons are really on a
like for like basis, the data provided by Tokyo
appears to justify comparison.
Other world cities have adopted a more longterm
approach to their water infrastructure.
For instance, the Hong Kong Water Supplies
Department has launched a programme to
replace 45 per cent of its mains that are some
30 years old, over the next 15 years 32,33 .
43

44 The Mayor’s draft water strategy
in the cost-effectiveness of leak reductions
and mains renewal. The present effort needs
to be sustained in the long term, and not
relaxed once the industry average has been
reached (even accepting that the industry
average will itself have been reduced by
Thames Water’s improved performance).
3.12 Replacing the Victorian mains inevitably
affects traffic. The Mayor wants to minimise
the impact of road works associated with
utility works on Londoners and has therefore
agreed with the utility companies a code of
conduct, which commits them to measures
such as improved signage and working
outside peak hours where possible. He has
also secured a commitment from Thames
Water to start plating sites where work
is temporarily halted, so traffic can flow
smoothly 34 . In the long-term benefits, the
mains renewal will reduce the potential for
future bursts and leaks, minimising the need
for more work in the future.
Proposal 2 Thames Water should, through
its Water Resources Management Plan, aim
to achieve the best UK industry standard for
leakage by 2035, in order to bring London in
line with the best standards of world cities.
Pressure in the water mains
3.13 Should a main or supply pipe fracture or
burst, then clearly the higher the pressure
the higher rate of water loss. Water
companies currently have a duty to provide
water at a minimum pressure standard.
Historically much of London has enjoyed
water pressures well in excess of the
minimum standard. Some companies are
looking to adjust their pressure levels to help
reduce leakage and to bring them closer to
the industry standard. However, reducing
mains pressure (to albeit legal standards) can
have implications for high-rise properties
that may need to install additional pumps.
This has been a particular concern to London
councils. Dropping mains pressure is also a
potential problem for fire fighting.
3.14 In response to these concerns, Thames
Water has undertaken to meet half the cost
of installing booster pumps in all buildings
that need them as a result of reduced
mains pressure. In addition, the company
is offering interest free loans for a period
of five years to cover the remainder of the
cost. Care also needs to be taken to avoid
any risks of back-flows when pressures
are reduced which could otherwise risk
contaminating water supplies.
Find and fix
3.15 Whereas the Victorian Mains Replacement
programme is proactive and long-term, the
short-term response is to ‘find and fix’ leaks
in the existing network. In 2007/08 Thames
Water dealt with some 70,000 leaks in the
network. Many of these leaks are unseen
on the surface and have to be detected
underground. However, some are bursts
that lead to significant disruption of traffic
and, at worst, the flooding of buildings.
London Underground and Thames Water
have a regular four-weekly liaison meeting
at which suspected water main leaks
affecting underground assets are identified

for investigation, and the results of these
investigations and remedial actions are
reported. This has resulted in a significant
reduction in long-standing problems, and
ensures that newly identified locations are
properly discussed.
Supply pipe losses
3.16 A sizeable proportion of water lost
through leaks comes from supply pipes
linking individual buildings to the mains.
Households are responsible for any leaks
in these supply pipes, and most companies
offer a free leak detection and repair service
the first time a problem arises. In London,
only a fifth of houses and flats have a water
meter and it is unlikely that householders
will be aware of such a problem. Although
water meters inside the home are valuable
for customers to monitor their water use,
internal meters fail to pick up leaks outside
the property. A solution would be to have
boundary meters with ‘smart’ technology
to relay information to a display inside the
home. Thames Water is installing boundary
meters with its ‘Leakfrog’ technology 35 as
part of the integrated demand management
programme as these help to identify
customer supply-side leakage.
Metering
3.17 Research has shown that household
metering reduces water use by between
ten and 15 per cent 36 . The need to measure
water use in order to manage it adequately
is a strong argument in favour of universal
water metering. With identification of
eastern England as an area of water stress,
another argument in favour is that it can
help to conserve water. It is not surprising
that people tend to use less water when
they pay for it by volume used rather than
through a standard charge that does not
reflect the amount used.
3.18 7.6 million people live in London,
in 3.2 million households. Of these,
22.7 per cent have water meters, which
are used as a basis for charging for water.
This level is lower than that for the UK as a
whole (around 26 per cent) but is increasing
at two per cent per annum. In comparison,
many of our European neighbours have
achieved near-universal metering, with the
UK and Ireland as the only OECD countries
without such metering.
3.19 London’s low current and low forecast takeup
of meters is often attributed to London’s
high proportion of flats. In London flats
and maisonettes account for 45 per cent of
the total number of dwellings, substantially
higher proportion than any other region
(the next largest is the South East, with
15 per cent) 37 . Flats are often difficult
to meter because of the complexities of
their plumbing that was not installed with
metering in mind. Nevertheless 52 per cent
of buildings in the capital are detached, semi
or terraced which can be metered relatively
easily – so London can make some relatively
easy gains.
3.20 Although all new homes are metered, in
some cases water companies in London have
allowed ‘bulk meters’ to be installed in new
45

46 The Mayor’s draft water strategy
blocks of flats rather than individual meters
(ie one meter at the base of the block with
the bill split between the tenants). This has
led to letters of complaint to the London
Mayor when residents have been unable to
have individual meters fitted. In response,
a detailed investigation of the problems of
metering flats was commissioned from Ove
Arup & Partners 38 . Also, references to universal
metering in other countries means bulk
metering rather than meters for each flat 39 .
Proposal 3 The Mayor will work with water
companies and other partners to support
the rapid introduction of water metering
throughout London. The Mayor considers
that all houses in London should have meters
installed by 2015, and all blocks of flats by
2020. All new flats in London should have
an individually metered water supply. Tariff
arrangements should encourage the efficient
use of water but protect vulnerable and lowincome
households.
Figure 3.1 The components of household water
demand
Source: Environment Agency 40
Outdoor use 3%
Dish washer 3%
Washing machine 12%
Kitchen sink 10%
Bath 24%
Shower 20%
Basin 9%
WC 19%
3.21 Water meter tariffs are considered in Chapter
6 (paragraphs 6.21 to 6.30).
Demand management
3.22 Demand management is an umbrella term
for a variety of policies or measures that
serve to control or influence the use of
water. There are three strands of demand
management:
• Water efficiency. Changing behaviours
and/or using appliances and fittings that
use less water for the same result.
• Water conservation, which looks at using
less water through a change in behaviour.
An example would be taking a shower
rather than a bath.
• Reclaimed water, which looks at using
rainwater or grey water for non-potable
water (ie non-drinking water) needs.
Water efficiency in new homes
3.23 Household water use is dependent on
the water fittings and appliances used in
the home. It is the product of the level of
ownership of the fitting or appliance, the
frequency of use and the volume each use.
Nationally, we use an average of 150 litres
of water per day and, although our water is
treated to a drinking water standard, most
of this water is used for toilet flushing and
washing (see Figure 3.1). Within this ‘average’
water use varies quite widely according to
behaviours, cultures and lifestyles.
3.24 In December 2006, the government
published its Code for Sustainable Homes 41 .
The code has been introduced to improve
sustainable home building practice. It is a

standard for key elements of design and
construction, which affect the sustainability
of a new home, and will form the basis for
future reviews of the Building Regulations.
It sets a minimum standard for water use,
together with a system of additional code
points, as shown in Table 3.1. The code aims
to provide a general incentive for developers
to build to greener standards, and Code
Level 3 (equal to or less than 105 litres per
person per day) will be required for publicly
funded developments. Code Level 3 has also
been incorporated into the London Plan as a
requirement for all new housing in London
3.25 Government also made a commitment in
its Housing Green Paper 43 that it would
be setting new standards to achieve an
improvement of almost 20 per cent on
current average usage to support sustainable
water use in all new homes across England
and Wales. To fulfill this commitment an
amended Part G of the Building Regulations,
Table 3.1 Code for Sustainable Homes
which sets a maximum daily usage standard
of 125 litres per person per day, will come
into force in October 2009.
3.26 Research undertaken for the Environment
Agency, Assessing the cost of compliance
with the code for sustainable homes 44 , shows
that the cost of meeting the 100-120 litres
per person per day standard is just £189-
£284 above the cost of providing current
fittings and equipment in homes. Similarly
saving water in the home, which often
reduces the production of hot water, can
make savings for householders’ energy bills.
3.27 Cyril Sweett undertook a detailed study of
the costs of compliance with the Code of
Sustainable Homes 45 looking at six different
types of houses:
• A traditionally built detached house
(116m 2 )
• A traditionally built end of terrace house
(101 m 2 )
Issue Measurement criteria Points awarded
Internal potable water
consumption
External potable water
consumption*
Where predicted water consumption (calculated using
the Code water calculator) accords with the following
levels:
≤ 120 l/p/d (Mandatory for levels 1& 2)
≤ 110 l/p/d
≤ 105 l/p/d (Mandatory for levels 3 & 4)
≤ 90 l/p/d
≤ 80 l/p/d (Mandatory for levels 5 & 6)
For providing a system to collect rain water for use in
external irrigation/watering eg water butts
One of the following point
scores
1.5
3
4.5
6
7.5
*Code excludes a water consumption standard for outside water use. This ranges between 5-10 l/h/d and is proportional
to availability and size of garden. Source: Department for Communities and Local Government 42
1.5
47

48 The Mayor’s draft water strategy
• A traditionally built (ie non-framed) low
rise apartment (59 m 2 net occupied area)
• A concrete framed medium/high rise
apartment (75 m 2 net occupied area)
• Two homes built using modern methods
of construction and compliant with the
requirements of English Partnerships’
Design for Manufacture (DfM) competition:
- An end of terrace house based upon the
Weber Haus product
- A mid terrace house incorporating a
centralised CHP system referred to in the
report as the ‘SixtyK House’ based on its
estimated construction cost of £60,000.
3.28 They calculated the baseline cost of
constructing each type to comply with
the 2006 Building Regulations. They then
calculated the additional cost of complying
with the different levels of each element of
the Code. Table 3.2 shows the additional
costs of meeting Code levels 3 and 4 and
levels 5 and 6 for water. Code levels 1 and 2
could be met at no additional cost. The costs
of meeting those Code levels for energy is
significantly higher.
3.29 The costs are based on assumptions
that certain fixtures and fittings will reduce
water consumption in new homes to the
levels required. However, we need far more
houses and flats built to these standards,
and occupied for some time, before we
can be assured that the assumptions are
correct. There are still very few houses built
to the Code level 3 standard, and those
built to Code levels 5 and 6 can best be
described as ‘prototypes’.
Proposal 4 The Mayor believes that, where
possible, all new homes should meet the
highest level of the Code for Sustainable
Homes for water consumption.
Water efficiency in existing homes
3.30 Great efforts are being made to achieve
higher water efficiency standards within
new homes, however the greatest scope
for improving water efficiency is through
London’s 3.2 million existing homes.
Improving water efficiency in existing
homes can be achieved through installing
more efficient fittings and appliances,
plus improving the resident’s water use
behaviours. Adapting existing appliances can
be inexpensive and relatively simple, such
as fitting low flow showerheads, inserting
aerators or flow restrictors into taps or
installing variable flush devices to existing
toilets. With householders likely to move
on average every 7-15 years 46 there are
opportunities to encourage refurbishment to
be water efficient.
3.31 The annual Halifax Home Improvement
Survey 47 tells us that homeowners consider
that a modern, fitted kitchen adds the most
value to a property with almost a third
believing that a modern fitted kitchen is
the main feature to improve the monetary
value of a home. The kitchen and bathroom
were also voted the top two rooms that
homeowners most wanted to change, at 25
and 16 per cent respectively. This presents a
huge opportunity to encourage and deliver
water efficiency change, as the kitchen and

athroom combined use at least 80 per cent
of total residential water use (see Figure 3.1).
3.32 The Environment Agency report Water
Efficiency in the South East of England,
Retrofitting existing homes 48 shows
that retrofitting existing homes has the
potential to save an extra 31 litres/person/
day over the current Building Regulations
requirements relatively quickly with existing
and simple technology. Three Regions
Climate Change Group report Your home
in a changing climate 49 identifies and
quantifies the options, costs and benefits for
retrofitting existing homes to adapt to the
impacts from a changing climate including
water stress, flooding and overheating.
3.33 A theoretical case study of a typical semidetached
house with a family of five,
calculated that a full suite of retrofitted
Table 3.2 Costs of meeting Code water consumption targets for housing
water saving items and appliances, could
save up to 109 litres/person/day. The
associated hot water savings equated to
reductions in energy use of 1430kWh/year,
approximately £132 off energy bills and a
CO 2 emission saving of 600 kilogrammes/
year. Even a simple retrofitting exercise
consisting only of low-flow showers,
WCs and taps, delivered water savings
of approximately 50 litres/person/day 50 .
However, as with new construction (see
paragraph 3.29 above) there are still too few
large-scale examples to be certain that the
anticipated water savings will be achieved in
all cases.
3.34 Figure 3.2 illustrates the relationship
between water use in the home (centre),
overall carbon emissions associated with
water supply and wastewater treatment
(left), and the carbon emissions from all
House type Base cost* Code level 3 and 4 Code level 5 and 6
Additional cost % addition Additional cost % addition
Traditional detached house £91,206 £125 0.1% £2,645 2.9%
Traditional end terrace house £75,235 £125 0.2% £2,645 3.5%
Traditional low rise flat £79,200 £125 0.2% £805 1.0%
Traditional high rise flat £124,500 £125 0.1% £805 0.6%
‘Weber Haus’ £59,958 £125 0.2% £2,645 4.4%
‘SixtyK’ house £60,000 £125 0.2% £2,645 4.4%
• Base cost is the cost of construction to comply with the 2006 Building Regulations. Code levels 1 and 2 are met within
the base cost.
Code levels 5 and 6 were met by adding grey water recycling or rainwater harvesting systems to meet 30 per cent of the
water requirement. It is worth noting that the Cyril Sweett cost estimate for Code levels 5 and 6 flats are in line with the
Tokyo experience (see Case Study on page 55) that water reuse systems add up to 1 per cent to construction costs.
These cost do not include land costs, so the cost of meeting the Code standards will be a significantly lower percentage of
the overall sale price of new houses and flats.
49

50 The Mayor’s draft water strategy
activities in the home (right). The left-hand
pie chart shows that water use in the home
accounts for 89 per cent of all the carbon
emissions resulting from water use. Water
abstraction, treatment and supply together
with wastewater collection and treatment
only accounts for just 11 per cent.
3.35 The right-hand pie chart shows that
water use accounts for 27 per cent of
carbon emissions from the home. This is
made up of 19 per cent from the heating
of water for baths, showers, and hand
washing and washing up. Water-using
appliances including dishwashers and
washing machines account for the other
nine per cent. Taking a shower rather than a
bath – in other words, using less hot water
– will therefore only have a relatively small
effect on the carbon emissions from water
supply but a much bigger effect on carbon
emissions from the home.
Figure 3.2 Carbon emissions resulting from water supply, use and wastewater treatment
Carbon emissions from
domestic water supply
and wastewater treatment
Water supply 0.4%
Water abstraction 1/6%
Water treatment 2%
Wastewater treatment 7%
Water in the home 89%
Carbon emissions from
water use in the home
WC 7%
Basin 11%
Bath 14%
Kitchen sink 21%
Shower 12%
Washing machine 16%
Dishwasher 19%
Sources: Environment Agency 51 (left chart) Energy Saving Trust (centre chart)
Carbon emissions from
all energy use in the home
Other appliances 9%
Cooking 3%
Water-using appliances 9%
Hot water 18%
Lighting 5%
Space heating and cooling 54%

3.36 Table 3.3 shows the potential savings in
water usage, water and energy costs and
carbon emissions that can be achieved
through the introduction of various water
saving devices and changes in behaviour.
3.37 The government, in its water strategy
for England Future Water puts forward
a ‘Vision for 2030’ in which per capita
consumption of water is reduced through
cost effective measures, to an average of
130 litres per person per day by 2030, or up
to 120 litres per person depending on new
technological developments and innovation.
But since publication in February 2008, the
government has given no guidance as to
how these standards are to be achieved.
Whilst none of the four water companies
serving London have adopted this as a
planning target in their draft Water Resource
Management Plans, Table 3.3 and experience
Baseline: Standard London house
with high flow mixer shower
Scenario 1 Retrofit: Showerheads,
Taps, Cistern insert
m 3
year
Water
cost
Energy
cost
from other countries such as Australia does
suggest that 130 or 120 litres per person per
day could be achieved by 2030. The Mayor
therefore supports 130 litres per person per
day as a medium-term target for reducing
domestic water consumption.
3.38 Retrofitting London’s 3.2 million existing
homes has become an essential climate
change action for both reducing London’s
carbon emissions and improving our water
efficiency. The London Plan 52 and London
Housing Strategy 53 both contain policies
to improve the environmental performance
of London’s existing housing stock. The
Mayor is working with boroughs and other
partners to develop a successor standard to
the current Decent Homes Standard, which
will include water efficiency objectives for
social housing refurbishment. The Mayor is
also directing a significant share of London’s
Table 3.3 Reduced household water use, cost and carbon emissions through retrofits and behaviour changes
Scenario 2 Behaviour changes:
Replace bath/long shower with
short shower
Scenario 3 Retrofit and behaviour
changes combining Scenarios 1 & 2
Total
cost
Kg CO 2
year
Notes
192 £283* £277 £560 1369 Weekly: 5 showers and 2 baths per
person. 10 litre toilet.
157 £232 £210 £442 1038 Showerhead 11 litres per minute for
7 minutes. tap aerators and Ecobeta
toilet insert
150 £221 £260 £421 988 5 minute shower instead of daily bath
or long shower
107 £158 £148 £306 719 Shower, toilet and tap retrofits.
5 minute showers
• Based on the average Thames Water bill for water and sewerage services in 2008/09.
Calculation based on Energy Saving Trust data.
51

52 The Mayor’s draft water strategy
housing pot towards improving the homes
occupied by the most vulnerable households
in London.
3.39 Londoners need proper water efficiency
labelling of household appliances at the
point of sale if we are to become more
water efficient. The Mayor welcomes the
Bathroom Manufactures Association’s recent
introduction of voluntary labelling scheme
for water efficient bathroom products, plus
the use of the Waterwise Marque to further
promote water efficient products. However
there are over 20 different water efficiency
labelling schemes operating in the UK at
present. The Mayor would support the
introduction of a national scheme, with a
water efficiency ranking system that is clear
for consumers.
Proposal 5 The Mayor has announced a
commitment to improve the energy efficiency
of London homes. This strategy highlights
the need for existing homes to become more
water efficient. Improving energy and water
efficiency at the same time is both sensible
and the least cost way of helping Londoners
to control their energy and water bills as well
as to reduce their green house gas emissions.
Changing behaviours
3.40 Saving water in households depends both on
the fittings and appliances in the home and
how they the occupants use them. A water
efficient house with inefficient occupants
could in effect use more water than a
standard house with a water aware family. For
example, the water used in a shower depends
on the length of the shower as well as on the
shower design. A water efficient shower may
have a flow rate of six litres of water a minute,
but used for ten minutes will use 60 litres of
water; a less efficient shower with a flow rate
of nine litres of water used for five minutes
will use only 45 litres of water.
Proposal 6 The Mayor will work with the water
companies, the Environment Agency, and
other partners in joint programmes to raise
awareness of the benefits of water efficiency,
including the possible savings that they can
achieve through their water and energy bills.
3.41 The benefits of partnership working were
demonstrated in the 2006 drought when
the GLA worked closely with Thames
Water on its large-scale water efficiency
campaign. The significant savings made
as a result of hosepipe bans, and also by
customers voluntarily reducing their water
consumption, avoided the introduction of
more severe restrictions.
Water efficiency in commerce
3.42 So far the Water Strategy has focused on
domestic water use. However water use
for non-domestic purposes also adds to
demand for water, and is an area where
water savings can also be achieved. In
London, non-domestic use accounts for
29 per cent of water consumption. The
Office of Government Commerce set a
best practice benchmark for water use in
office establishments of 6.4 m 3 per full time
employee per year. Other organisations
have set their own internal targets for water

use on their premises. For example, the
Environment Agency has set itself a target
of 5.1 m 3 per full time employee per year
for 2006/07. In the GLA, non-potable water
from a borehole cools City Hall, London, and
then diverts into the toilet cisterns. Hence
the potable water use in City Hall is low.
3.43 Non-domestic or commercial water use
is divided into non-service and service
sectors 54 . Commercial water use for
Thames Water’s London resource zone
for 2006/07 is estimated to be 412 Ml/d,
with 82 per cent attributed to the services
sectors and 18 per cent to non-services.
Leakage from commercial supply pipes
was some 1.5 per cent of total commercial
water delivered. Thames Water estimates
that whilst overall commercial demand
will grow over the next 25 years by some
eight per cent, the non-service sector’s
demand will reduce by 32 per cent. This
will be offset by an increase of 18 per cent
from the services sector.
Figure 3.3 The components of non-household water consumption
3.44 Commercial water efficiency therefore has
a significant potential to save water, for
example buildings with high occupancy
rates, such as schools, hotels and office
blocks, could replace urinals with waterless
varieties, making significant savings (a
standard urinal can use around six to ten
litres of water every flush). Thames Water’s
‘Liquid Assets’ project has shown significant
saving from water efficiency in commerce.
The project, launched in September 2006,
embarked on a water audit programme
for the public sector, with over 240 public
sector sites (ranging from primary schools to
sports centres) participating in a water audit
that identified potential leaks and made
recommendations on how to reduce water
consumption. In addition, Thames Water
provided funding for some sites to install
recommended water efficient technologies.
Over 4,300 measures have been funded and
installed, including new urinal controls, push
taps and cistern devices with reported saving
in the region of 500,000 litres per day.
Other services 45.9%
Agriculture, horticulture, forestry and fishing 1.4%
Hotels, bars and restaurants 16.0%
Wholesale and retail 6.1%
Education and health 17.6%
Other manufacturing 3.1%
Transport and manufacture of transport equipment 3.3%
Food and drink manufacture 6.6%
53

54 The Mayor’s draft water strategy
3.45 Businesses that want to know more about
how they can save water should contact
their water supplier for advice. Thames Water
(like many other water companies) offer
free water audits to commercial customers
and its Water Regulations Audit Programme
offers technical advice on water saving
devices and measures. Envirowise offers
UK businesses free, independent advice
and support on ways to increase profits,
minimise waste (including water use)
and reduce environmental impact 55 . The
Enhanced Capital Allowance (ECA) scheme
allows businesses to claim 100 per cent first
year capital allowances on investments in
technologies and products included in the
ECA list of water efficient technologies 56 .
Table 3.4 Rainwater and grey water sources and end use
Reclaimed water
3.46 By ‘reclaimed water’, this strategy refers
to the use of rainwater and grey water for
non-potable uses, such as toilet flushing and
outdoor water use. The public has a general
understanding of water distribution based
on a single supply of drinking-quality water.
Changing their acceptance of a single supply
system to two separate systems – one for
drinking-quality water and another of lower
quality water for non-potable uses – is a key
to the success of reclaimed water.
3.47 There are no UK specific legal requirements
defining an acceptable standard for
grey water However, rainwater correctly
collected and stored can be used for toilet
Rainwater Grey water
Sources End use Sources End use
Roof guttering Toilet flushing
Car washing
Plant watering
Table 3.5 Acceptable water quality for reclaimed water
Toilet flushing
Plant watering (non-edible plants)
Car washing (spray)
Wash basins
Baths
Showers
Use Requirement
Source: BSRIA Water reclamation standard 58
Total coliforms
(counts/100ml)

flushing, clothes washing and outdoor
use without further treatment. Table 3.5
sets out possible acceptable water quality
properties for different applications. BSI is
Case study | Roppongi Hills, Tokyo
Whilst the use of reclaimed water, both
rainwater and grey water, is regarded as novel
in London and the UK, it has been used for
many years in other cities such as Tokyo
where it is regarded as routine. Sumida Ward
(equivalent of a London borough) has been
promoting rainwater harvesting since 1984 and
now requires all new buildings with a site area
of more than 500 m 2 to install such systems.
Tokyo Metropolitan Government applies a less
stringent standard across the whole of the
city, requiring new buildings with a floor area
of more than 10,000 m 2 to install rainwater-
harvesting systems.
Grey water reuse is also well established. A
notable example of the integration of rainwater
harvesting with grey water reuse is the
Roppongi Hills development in central Tokyo.
The filtration plant is illustrated here. This is
mixed use redevelopment integrating office,
residential, hotel, retail, and cultural functions
with parks and plazas. The project, covering
approximately 11 hectares, with a total floor
area of 724,000 m 2 , is one of the largest
redevelopment projects in Japan.
Reclaimed water (16 per cent rain water and
27 per cent grey water) meets 43 per cent
looking at developing a British Standard for
rainwater harvesting systems and UKRHA
(UK Rainwater Harvesting Association)
is currently working on a rainwater Code
of demand in the building complex. The
developer, Mori Building Co. Ltd., has many
years of experience in building and operating
such systems in its developments having
installed the first grey water reuse system
in the Toranomon 37 building in 1981. They
estimate that reclaimed water systems add as
little as one per cent to construction costs.
Clearly, design expertise, engineering
capability and operating standards are
available internationally for the satisfactory
operation of water reclamation systems.
London needs to move towards incorporating
such systems in large new developments in
the city in order both to stem the growth in
water demand and to minimise discharges to
the sewer system.
55

56 The Mayor’s draft water strategy
of Best Practice. Defra intend to produce
appropriate standards for non-potable
water. Adequate training and monitoring
should be provided in order to minimise
cross-connections and the risk of health
Case study | Water neutrality in the Thames Gateway
The redevelopment of the Thames Gateway is
the largest brownfield regeneration project in
Europe. 160,000 homes and 225,000 jobs will
be created in an area that covers the east of
London and parts of Kent and Essex. As this
area is already ‘seriously’ water stressed, the
Environment Agency has proposed a concept
of ‘water neutrality’ for the Thames Gateway,
where existing development is made more
water efficient to provide the water for the
ultra water efficient new development. The net
demand does not therefore increase despite an
increase in development. This concept could
be applied to London to ensure that London’s
demand for water does not increase despite a
net increase in population.
The Environment Agency lead a year-long
feasibility study Towards Water Neutrality in
the Thames Gateway 57 , jointly funded by the
Environment Agency, Communities and Local
Government and Defra. The study explored
the feasibility of what could be achieved
through the management of demand for water
in the Thames Gateway. The report, which
was published in November 2007, concluded
that the Thames Gateway could use the same
amount of water in 2016 as it does now,
related problems. For instance, a relatively
simple way of avoiding cross-connections
could be requiring different colour pipes
for the drinking water and the non-potable
water supply.
providing that an ambitious water demand
management programme is implemented as
part of development in the area. According to
the study the measures that have the greatest
potential in achieving water neutrality include:
• New homes – Building new homes to
higher water efficiency standards offers
substantial water savings and could
account for 9-17 per cent of water saved.
• Retrofitting – Improving the water
efficiency of existing homes through
retrofitting water saving appliances could
account for 23-47 per cent of water
saved. This includes simple ‘fit and forget’
measures such as variable flush toilet
devices; low flow showerheads and low
flow tap inserts accounts.
• Metering – Metering of new and
existing homes could account for
ten per cent of water saved.
• Variable tariffs – Introducing variable
tariffs could account for 22 per cent of
water saved (under this tariff structure
the cost for each unit of water above a
certain threshold is charged at a higher
rate, encouraging consumers to use
water wisely)

3.48 The use of reclaimed water includes water
used for watering planted areas, washing
paving and similar purposes within the
development where water from the public
supply would otherwise be used. Chapters
4 and 5 give further consideration to the
use of rainwater and grey water to meet
domestic water needs respectively.
Drinking water quality and
bottled water
3.49 So far there has been little mention of
drinking water in this strategy. This is largely
down to the excellent quality of drinking
water. In the UK our drinking water is of a
very high standard, and among the best in
the world. Nevertheless, misconceptions
associated with the quality of tap water, in
terms of taste and perceived ‘unhealthiness’
of tap water, can encourage people to
purchase bottled water. In terms of cost, tap
water is roughly 1000 times cheaper than
bottled water, with 50 glasses of tap water
costing one penny. Bottled water, per litre,
can be more expensive than petrol.
3.50 The Mayor and Thames Water launched
the London on Tap campaign in February
2008 to promote tap water in London’s
restaurants, cafes and pub. It aims to:
• raise awareness of the high quality of
London’s tap water, the contribution of
bottled water to climate change, and the
benefits of drinking water to health and
wellbeing
• encourage customers in bars and
restaurants to ask for tap water rather than
feeling obliged to ask for more expensive
bottled brands
• encourage restaurants, bars and hotels
across London to proudly serve tap water
to customers, giving them a real choice
about what water they can drink
• Last December, the Mayor announced
the winner of a competition to design a
carafe that will be used to serve tap water
in restaurants, cafes, bars and hotels
throughout the capital.
The Mayor also supports the concept of
drinking water fountains and is keen to see
them wherever possible in London.
Proposal 7 The Mayor will work with the
water companies and other partners to raise
awareness of the high quality of London’s tap
water, the contribution of bottled water to
climate change, and the benefits of drinking
water to health and wellbeing. He will also
encourage restaurants, bars and hotels across
London to serve tap water to customers.
3.51 In 2004, over 1.7 billion litres of bottled
water were sold in the UK. While this
accounts for a very small proportion of
total water use, because of the transport
and packaging involved, bottled water has
a much higher carbon footprint per litre
than water supplied via the tap – more than
300 times the carbon dioxide emissions per
litre in the case of some imported brands.
Further information on the environmental
impact of bottled versus tap water is given
in report The Environmental Impact of Food
Consumption and Production prepared for
Defra in 2006 59 .
57

58 The Mayor’s draft water strategy

4 Managing rainwater
4.1 This chapter is concerned with the
drainage of rainwater away from homes
and businesses in London. Following
this, Chapter 5 examines the removal of
wastewater. In large parts of inner London,
a combined drainage network (called the
combined sewer) takes both rainwater
and wastewater away from buildings. The
problems associated with the combined
system are considered in Chapter 5.
4.2 Rainwater is either lost through evaporation,
seeps into the ground to replenish
groundwater levels, flows over the ground
and returns to streams and rivers, or enters
the drainage systems and then flows on to
a sewage treatment works. In the parts of
London not covered by the combined sewer,
the surface water drains carry rainwater from
pavements, road surfaces and rooftops into
local rivers and streams (see Figure 2.9).
4.3 Over the past 40 years, the intensity of
rainfall has increased during the winter
months across the country. The occurrence
of more than 15 millimetres of rain on a
day (referred to as heavy rainfall days) has
become more frequent in winter. Since
1989, heavy rainfall days have consistently
contributed more than ten per cent of the
seasonal total rainfall; this was not always the
case prior to 1989. Heavy rainfall can quickly
overload the drainage system, as well as carry
debris and pollutants from paved areas, such
as roads and car parks, and from gardens into
otherwise clean rivers, stream and ponds.
4.4 In 2007 a submission to the Shadow Cabinet
entitled A Blueprint for a Green Economy 60
notes that we need ‘Slow Water’. Slowing
water down through the use of green roofs
and sustainable urban drainage systems
filters and removes pollutants. The Draft
Flood and Water Management Bill now
proposes significant changes to the way in
which we manage surface water.
Policy 2 – Drainage in London
The Mayor proposes the following
hierarchy for the drainage of rainwater:
1 Store rainwater for use later
2 Use porous surfaces to let rainwater
to soak into the ground where soil
conditions allow
3 Slow the runoff by directing rainwater
into ponds or open water features for
gradual release to a watercourse
4 Slow the runoff by directing rainwater
into tanks or sealed water features for
gradual release to a watercourse
5 Discharge rainwater direct to a
watercourse
6 Discharge rainwater to a surface
water drain
7 Discharge rainwater to the combined
sewer, as a last resort.
4.5 The flood risk principles (from LIFE
Handbook 61 ) provide a useful guide to
understanding where application of Policy 2
is important, so as not to increase the risk of
fluvial flooding from surface water runoff:
• upper catchment – ‘let rain slow’
• middle catchment – ‘let rivers flow’
• lower catchment – ‘let tides go’

60 The Mayor’s draft water strategy
The Environment Agency’s Thames
Catchment Flood Management Plan
supports this as it emphasises the
importance of surface water management
and greater attenuation in a number of
London river catchments that are susceptible
to rapid flooding from thunderstorms,
for example, the Rivers Ingrebourne and
Ravensbourne. Given the short lead-in times
on a number of the London rivers emergency
response and flood awareness are also
particularly important.
Rainwater use
4.6 Solving the problem of surface water flooding
by enlarging the drainage system alone, even
if technically feasible, would be prohibitively
expensive. Using rainwater before it goes
down the drain can help to relieve the
pressures on the drainage system. Instead of
using water from the mains, householders
could use rainwater for toilet flushing, clothes
washing and outdoor uses. Figure 3.1 shows
that these uses account for over a third
of all water used within a house. Correctly
collected and stored, rainwater can meet all
these requirements with little treatment. The
appliances should still have a connection to
the public mains supply to guarantee that
water is available even at times of low rainfall.
4.7 The treatment of rainwater will depend on
the source of rainwater and its intended use.
For instance, rainwater collected from clean
surfaces and filtered to remove nutrients
is likely to be low in harmful bacteria and,

if only used for toilet flushing or garden
watering, will require little disinfection.
Yet, regular cleaning of the collection
area is important to prevent rainwater
contamination from bird droppings.
Managing surface water runoff
4.8 The increase of heavy rainfall days and the
growth in hard surfaces mean the existing
surface water drains can no longer cope
with the rise in runoff. In turn, this can
lead to a greater risk of flooding as surface
water drains are overwhelmed. Conventional
drainage systems, with pipes and sewers, are
designed to take surface water away from
streets and buildings as quickly as possible
and discharge it into the main sewers and
watercourses. Sustainable drainage systems
(SUDS) seek to mimic natural drainage,
managing more water above-ground, close
to the source, in order to reduce the volume
and speed of waters flowing into sewers and
watercourses after storms, and therefore the
risk of flooding.
4.9 More sustainable drainage, such as using
porous surfaces to let rainwater to soak
into the ground where soil conditions
allow, can avoid or reduce the need to
construct surface water drains to distant
outfalls. At the same time, it can improve
the environment through the creation of
habitats and the reduction of pollution.
Imaginative sustainable drainage schemes
can be developed as attractive landscape
features, providing habitat for aquatic
wildlife and interesting opportunities for
local people to enjoy access to nature. Green
roofs can provide another mechanism for
slowing rainwater discharge. The Mayor’s
supplementary planning guidance for
sustainable design and construction set the
standards for drainage in new developments.
Table 4.1 outlines these standards.
4.10 The Code for Sustainable Homes (referred
to earlier in paragraph 3.24) also has
criteria for the attenuation of surface water
run-off. This requires that surface water
run-off rates and annual volumes should
be no greater after new homes have been
built than before. Further requirements
apply where rainwater holding facilities or
SUDs are used to attenuate run-off into
either natural watercourses or surface water
drainage systems 62 .
4.11 In the past, householders faced few barriers
to increasing the amount of impervious
paving around their property. Paving front
Table 4.1 Supplementary planning guidance on Sustainable Design and Construction, 2006
Essential Standards Mayor’s Preferred Standards
Use sustainable drainage systems (SUDS) measures,
wherever practical.
Achieve 50% attenuation of the undeveloped site’s surface
water run off at peak times
Achieve 100% attenuation of the undeveloped site’s
surface water run off at peak times
61

62 The Mayor’s draft water strategy
gardens was a permitted development right,
and therefore could generally be carried
out without planning permission. Following
consultations in 2007, the government
accepted that, given the contribution of hard
standing to surface water flood risk, it would
restrict householders’ to porous surfaces.
Planning permission is now required for
impermeable surfaces in front gardens larger
than five square meters 63 .
4.12 The Draft Flood and Water Management
Bill will require developers to include
sustainable drainage, where practicable, in
new developments, built to standards that
reduce flood damage and improve water
quality 64 . It will also amend section 106 of
the Water Industry Act 1991 to make the
right to connect surface water run-off to
public sewers conditional on meeting the
new standards. It will give responsibility
for approving sustainable drainage systems
in new development, and adopting and
maintaining them where they affect more
than one property, to a SUDS approving
body, generally local authorities. The Mayor
supports the legislative changes proposed in
the Draft Flood and Water Management Bill
in respect of surface water management.
Proposal 8 The Mayor will encourage green
roofs rainwater harvesting, grey water
recycling and sustainable drainage through
planning policies in his new London Plan.
4.13 There are instances where surface water
drains have been connected to a foul sewer,
when connections to separate surface water
drains or watercourses were available and
would have been more appropriate. This is
discussed more fully in paragraphs 5.17 to
5.21. The proposed changes in the right
to connect to a public sewer will require
effective enforcement by Local Authorities.
Risks of flooding
4.14 In London, tidal and fluvial flooding presents
a significant risk. About 400,000 properties
are at risk from tidal flooding while about
100,000 properties are at risk from fluvial
flooding. Also at risk are the Underground
system, power supplies, telecommunications
and much other critical infrastructure. The
Thames Barrier and associated defences
protect those properties at risk of tidal
flooding to a very high standard so that
there is less than a 0.1 per cent chance
of flooding in any one year. Those at risk
from fluvial flooding are protected to only
a moderate standard, typically there is
between a one and five per cent chance
of flooding in any one year. The flood risk
from tidal flooding is therefore very low in
probability, but very high in consequence
and for fluvial flooding there is a moderate
to high probability, but with lower
consequences.
4.15 Flooding can have a significant effect on
people’s health and wellbeing. As well as
physical problems, such as colds and chest
infections, flooding can cause increased
levels of stress and anxiety, for example,
as a result of having to live in temporary
accommodation, paying for repairs and
dealing with insurers 65 .

4.16 With regard to tidal flood risk the
Environment Agency’s Thames Estuary
2100 Project is developing a tidal flood
risk management plan for London and the
Thames Estuary. The plan was released for
consultation in March 2009 66 and sets out the
range of options that can manage increasing
tidal flood risk over the next century.
4.17 Our options to reduce the probability
of fluvial flood risk are constrained.
Regeneration and redevelopment within the
floodplain offers the biggest opportunity
for reducing flood risk in London. Planning
Policy Statement 25: Development and Flood
Risk 67 and the Environment Agency’s Thames
Catchment Flood Management Plan (CFMP)
expand on this message:
• Flood defences cannot be built to protect
everything
• Climate change will be the major cause of
increased flood risk in the future.
• The floodplain is our most important asset
in managing flood risk.
• Development and urban regeneration
provide a crucial opportunity to manage
the risk
• Alongside this we need to re-create river
corridors so that rivers can flow and
flood more naturally. All of these issues
are addressed in more detail in the draft
London climate change and adaptation
strategy 68 .
Flooding from the surface water drains
4.18 Surface water flooding happens when
rainfall can neither soak into the ground nor
drain away through the drainage system.
Therefore, surface water flooding can result
from prolonged periods of rainfall, when rain
falls on ground that is already waterlogged,
or during very heavy rainfall, when the
intensity of the rainfall overcomes the
capacity of the drainage system.
4.19 Because so much of London’s surface
is concrete and tarmac, and therefore
impermeable to rainfall, we are very reliant
upon our drainage system to keep us dry.
However, the responsibility for drainage
currently rests with many agencies, including
Thames Water, the London boroughs (for
land drainage and the local road network),
Transport for London and the Highways
Agency (for their road networks) and private
landowners. In addition, no single agency
has responsibility for reporting or recording
surface water flooding when it occurs.
4.20 This confusion over responsibilities led the
Mayor to create a partnership involving all
the organisations with responsibility for and
information on surface water management
in London. The partnership, called the Drain
London Forum, undertook a scoping study
to assess how much was known about the
location and ownership of London’s drainage
network and to propose a process by which
information can be shared and maintained
in order to develop a regional Surface Water
Management Plan for London.
4.21 The scoping study recommends undertaking a
hierarchical assessment of surface water flood
risk in order to focus efforts on the areas most
63

64 The Mayor’s draft water strategy
likely to be flooded, or where flooding would
have the greatest impact. The Drain London
Forum members have agreed to continue
collaborating to enable this to happen.
4.22 The flooding in summer 2007 (see box
below) led the government to appoint Sir
Michael Pitt to undertake a review of the
summer floods, and his report, know as the
Pitt Review, was published in June 2008.
The government responded to the Pitt
Review in December 2008 and has given the
Environment Agency a strategic overview role
in relation to for all forms of flood risk, whilst
local authorities are responsible for preparing
local Surface Water Management Plans.
Proposal 9 The Mayor will work with partners
through the Drain London Forum to create
a strategic-level surface water management
plan for London by 2012. This plan will assist
boroughs in producing their Surface Water
Management Plans, will prioritise strategic
actions, and will enable a regional submission
to be made for government funding to
manage surface water flood risks in London.
4.23 Arising from the Pitt Review, consideration
also needs to be given to the ability of the
existing water infrastructure (such as water
treatment plants and pumping stations)
to cope with flooding. This includes giving
consideration to both the resilience of the
whole supply network, and the network’s
ability to cope with the vulnerability of
individual site. Measures need to be in place
to ensure that services can be maintained
across London during a flood event.
Ownership of drains and sewers
4.24 Surface water drains; including gullies;
culverts and sewers are in a wide variety
of ownerships. The sewerage undertaker
(Thames Water in the case of almost all of
London) is responsible for the public surface
water drains except for highway drains.
Each London Borough is responsible for
maintaining the highway drainage on its
public roads, and Transport for London for
maintaining drainage on the Transport for
London Road Network. In private roads and
parking areas, the road gullies and surface
drains are the responsibility of the owner(s)
or occupier(s) up to the connection with the
public network. Any sewer not vested with
the sewerage undertaker is a private sewer.
4.25 The government has long recognised the
problems of private sewers. Defra announced
on December 2008 its intention, from 2011,
to transfer all existing privately-owned
sewers and lateral drains that connect to the
public sewerage system into the ownership
of the sewerage companies 70 . In order to
ensure that, over time, no new stock of
private sewers and drains develops to replace
them, Defra proposes in the Draft Flood
and Water Management Bill 71 to introduce a
minimum design and construction standard
for all new sewers and lateral drains that
are to be connect to the public system
and to make their adoption by sewerage
companies automatic.
Flooding from groundwater
4.26 The majority of groundwater in London is
to be found in chalk layers of the ‘London

Basin’. The London Basin is synclinal
(U-shaped), with tens of metres of sands,
silts and clays overlaying layers of chalk over
most of the central part of London. Further
away from the centre of London, the chalk
comes to the surface (outcrops) forming the
higher ground to the north (Chilterns) and
to the south (North Downs). This geology is
illustrated in Figure 2.1.
4.27 Flooding from groundwater is a general term
that can refer to several different sources of
flooding. There are two broad categories:
• Groundwater flooding when groundwater
permeates above ground through a natural
process, usually some time after periods
of higher than average rainfall. In such
cases, flooding mainly occurs in the ‘dry
valleys’ of the chalk outcrop areas in south
London.
• Rising groundwater, when less water is
being abstracted and groundwater returns,
or ‘rebounds’, to its natural level. This
phenomenon occurs either in the deep
Case study | Summer 2007 floods
Nationally, more than 55,000 homes were
flooded in the summer of 2007. The wettest
summer since records began in 1766 caused
misery for hundreds of thousands of people
and more than £3 billion of insured losses. The
wet May and early June meant that the ground
was saturated and could no longer absorb
rainfall. Extreme rainfall in late June and late
July caused flash flooding where it fell and
chalk overlain by other geological deposits
or in the outcrop areas. In the former case,
the rise can cause structural damage to
deep foundations or flood underground
tunnels and service conduits. In the latter,
the rebound can flood properties, although
more generally it leads to higher flows in
the local chalk springs and streams.
4.28 Following prolonged periods of rainfall,
groundwater flooding can typically last
weeks, and tends to happen late in the
winter when groundwater levels reach a
peak. It usually results from poor drainage
or where proper attention has not been paid
to the nature of the site when constructing
buildings. High groundwater levels near
sewers can cause sewer flooding or make the
groundwater flooding more unpleasant and
a potential health hazard.
4.29 Our understanding of groundwater flooding
is far from complete. In spring 2006, the
Environment Agency assumed a strategic
then accumulated in rivers to extend the impact
to the floodplain. London did not escape
the effects of this wet weather, with 1,400
properties experiencing surface water flooding.
Whilst this weather was extremely unusual for
summer, climate change is predicted to cause
wetter winters with more extreme rainfall
events and therefore floods of this scale should
be expected in the future.
65

66 The Mayor’s draft water strategy
overview for monitoring groundwater
flooding. This forms part of its wider strategic
role in the new flood risk management
framework. As part of the strategic overview,
the agency will collate records, as well as
assess and monitor the problems associated
with groundwater flooding. At the same time,
the agency will consider ways to incorporate
the risk information into its flood risk
mapping strategy. This should improve the
awareness and understanding particularly for
those at risk, as well as for land-use planners
and developers.
Rising groundwater
4.30 In the latter part of the 19th century,
the chalk layers under London offered a
pollution-free source of water. With the
growth of industry, abstractions rose steadily
resulting in a widespread draw down of
the groundwater levels. These abstractions
gradually declined after World War II as
industry began to move away from London.
Some of the large public abstractions ceased
in the late 1950s and throughout the 1960s.
By the late 1970s, the rebound of chalk
groundwater levels was becoming noticeable.
4.31 Until very recently, rising groundwater
levels were putting London’s underground
infrastructure at a real risk from inundation.
In 1999, a team started to investigate how
best to resolve the problem. It concluded
that abstractions from London’s groundwater
should increase by 50 million litres of water
a day. Since then, the Environment Agency
has granted licences to take the surplus
groundwater. It is the Agency’s view that the
chalk groundwater levels are now stable and
no longer pose a significant threat to the
underground infrastructure
4.32 Interest in the use of groundwater for
cooling buildings has been growing
just at the time when the Environment
Agency’s concern has shifted from the
problem of rising groundwater levels to
the need to stabilise groundwater levels.
The Environment Agency has to issue
an abstraction licence in order to permit
groundwater to be used for cooling a
building, and the Agency is increasingly
requiring the water to be returned to the
aquifer after use in order to achieve stability
rather than for it to be drained away or
used for other purposes. The engineers
responsible for the refurbishment of the
Royal Festival Hall 72 originally proposed
an extensive distribution network for
groundwater on the South Bank but this
eventually proved impractical because of the
need to maintain stable groundwater levels.
4.33 London Underground’s Cooling the Tube
programme use a cycle of abstraction, use
for cooling and then re-injection of water,
so it has a minimal net impact on the actual
level of water resource. However, London
Underground is in competition with other
potential users for access to this scarce
resource for cooling. The Environment
Agency’s abstraction licensing process
operates on a first come, first served basis,
which means that London Underground is
at risk of finding that the abstraction limit
has already been reached in any area where

it is seeking to implement a Cooling the
Tube scheme.
Diffuse pollution
4.34 Besides pollution that originates from one
place (point source pollution), diffuse water
pollution can arise from many sources.
Individually the sources may be small and
diverse, yet their collective impact is often
damaging. Urban run-off typically contains
pollutants such as organic waste, pesticides,
fertilisers, hydrocarbons and nutrient
sediment. It is caused when rainfall is rapidly
washed from roads and other paved areas
into watercourses, in the absence of the
natural vegetation that would normally
allow such contaminants to settle out or
be absorbed. This problem is acute in the
London area because of the extent of urban
land use. Another source of contamination
is misconnections of properties to surface
water drains (see paragraph 5.17 below).
4.35 Unlike point source pollution, it is not as
easy to control diffuse pollution through
permits or licences. Here the regulatory
approaches require a greater degree of
subtlety. For instance, the better use of the
town and country planning system is central
to meeting the Water Framework Directive’s
requirements (see below).
Water Framework Directive
4.36 As noted in paragraph 1.7, the Water
Framework Directive 73 is designed to protect
and improve the environmental condition
of all waters. It applies to surface waters
(including lakes, streams and rivers),
groundwater, estuaries and coastal waters
(out to one nautical mile).
4.37 The directive aims to deliver ‘good
ecological/chemical status’ by 2015 based
on assessments of the chemical, physical
and ecological health of water bodies. The
Environment Agency has started to draw up
River Basin Management Plans 74 (RBMPs)
that assess the pressures and impacts on
surface water and groundwater bodies. As
part of the RBMP process, a Programme
of Measures will also be devised to meet
these objectives. However, there may be
cases where the actions required to meet
objectives are disproportionately expensive
or technically infeasible and the directive
allows lower objectives or longer timescales
to be set.
Rivers and canals
4.38 Pollution and the loss of habitat (often an
important buffer to diffuse pollution) led
to a deterioration in the quality of London’s
rivers in the early nineteenth century. It is
only in the last 40 years that there has been
an improvement in the quality of the River
Thames.
4.39 Despite the improvements in river quality,
many Londoners still think the Thames
contains little, if any, life. People typically
cite its muddiness (which is actually caused
by tidal action) and the floating rubbish as
evidence of its apparent ‘inert’ state. Yet,
more than 100 species of fish have been
found in the Thames Estuary in recent years,
many of them within London. The regular
67

68 The Mayor’s draft water strategy
sighting of grey heron and cormorant along
the Thames in central London is evidence
of its thriving fish life. Within the tributaries
of the Thames there is still much room
for improvement, with many rivers still in
flood protection concrete straitjackets and
degraded habitats making water quality
standards challenging to achieve, as can be
seen from Figure 4.1. The Mayor supports
the Environment Agency’s river restoration
strategies for north and south London, which
should be a catalyst for further improvement,
and working with the Agency and its partners
to support the London Rivers Action Plan.
4.40 The system of General Quality Assessment
is being discontinued in preparation for the
introduction of new procedures under the
EU Water Framework Directive, and 2004-
2006 was the last period for which all the
reaches of designated rivers in London were
graded. The new system will cover all bodies
of water and include rivers, canals, lakes,
groundwater, coastal waters and estuaries.
Figure 4.1 Chemical General Quality Assessment 2004-2006 for designated rivers in London

5 Disposal of wastewater
in London
5.1 Thames Water is the ‘sewerage undertaker’
for almost the whole of London (a small part
of Havering is served by Anglian Water). It
is responsible for collecting wastewater from
homes and businesses, and treating it at one
of the sewage treatment works listed below,
before returning the treated water back to
Table 5.1 London’s sewage treatment works
Sewage
treatment works
the River Thames or one of its tributaries.
Table 5.1 lists London’s wastewater
treatment works and Figure 5.1 overleaf
shows the network of sewers feeding into
them. It also shows the areas served by the
combined sewers and the separate foul and
surface water sewers.
Water course Catchment Consented
flow *
(m3/d)
Beckton Tideway Waltham Forest, Barking & Dagenham, Brent,
Camden, City of Westminster, City of London,
Ealing, Hackney, Hammersmith & Fulham, Haringey.
Islington, Kensington & Chelsea, Newham,
Redbridge, Tower Hamlets,
Crossness Tideway Bexley, Bromley, Croydon, Greenwich, Lambeth,
Lewisham, Merton, Southwark, Sutton, Wandsworth
Mogden Upper Tideway Barnet, Brent, Ealing, Harrow, Hillingdon,
Hounslow, Richmond Upon Thames, Hertsmere,
Slough, Three Rivers, Spelthorne, Windsor &
Maidenhead, South Bucks
Long Reach Tideway Bexley, Bromley, Croydon, Chelsham, Farleigh,
Tatsfield & Titsey, Limpsfield, Sevenoaks, Dartford
Riverside Tideway Havering, Barking & Dagenham, Redbridge,
Stapleford & Abbots
Deephams Leevia Salmon
Brook
Barnet, Brent, Enfield, Haringey, Waltham Forest,
Waltham Abbey, Broxbourne, Northaw & Cuffley
Hogsmill A Hogsmill River Kingston upon Thames, Sutton, Epsom & Ewell,
Banstead Village, Nork, Tattenhams, Preston,
Tadworth & Walton
Hogsmill B Beverley Brook 20,000
Beddington Wandle Croydon, Sutton, Chipstead, Kingswood, Caterham,
Warlingham, Whyteleafe and Woldingham
1,420,000 3,300
982,000 1,870
690,000 1,860
311,040 800
216,000 396
443,000 852
185,000 334
234,000 355
Population
served
(000s)
The ‘consented flow’ is the maximum volume of wastewater in cubic metres per day (m 3 /d) that the sewage treatment
work’s operating consent allows it to treat.

70
Figure 5.1 The London sewer system

5.2 The Environment Agency regulates the
release of sewage effluent to ‘controlled
waters’ by way of ‘consents to discharge’. The
consent limits the quantities of the various
pollutants that can be released and helps to
keep the quality of ‘controlled waters’ within
acceptable limits. ‘Controlled waters’ cover all
watercourses from rivers, lakes, reservoirs and
underground resources through to estuarine
and coastal waters. European legislation,
principally the Urban Waste Water Treatment
Directive (UWWTD) 75 , together with UK
regulations, set the general standards for
sewage treatment.
Policy 3 Disposal of wastewater in
London
The Mayor proposes the following
hierarchy for the disposal of wastewater:
1 Discharge wastewater to a foul sewer
2 Discharge wastewater to the
combined sewer, as a last resort.
This is the ideal hierarchy but it is recognised
in many areas there is limited choice.
Combined sewers
5.3 In the mid 1800s, Sir Joseph Bazalgette
designed and initiated the building of
London’s combined sewers. The sewers, still
in operation today, remove wastewater and
rainwater in the same pipe from properties
in central London. In order to avoid the
flooding of streets and properties with
raw sewage during intense rainfall events,
Bazalgette designed a series of overflow
outlets from the combined sewers (see
Figure 5.2) into the tidal River Thames and
its tidal tributaries ( together referred to as
the Thames Tideway. There are now some
57 such outlets, known as Combined Sewer
Overflows (CSOs), which allow diluted storm
sewage (excess sewage and rainwater) to
spill untreated into the Thames Tideway.
5.4 The expansion of the area served by the
combined sewers, together with population
growth and an increase in impermeable
surfaces, has resulted in greater flows
through the sewers in wet weather. During
dry spells the sewers have enough capacity
to cope with flows. However, during rainy
71

72
periods the sewers quickly fill up with
rainwater. Such is the strain on the system
nowadays that even relatively moderate
rainfall can trigger an overflow. Discharges
occur at some CSOs between 50 to 60 times
each year. Widespread heavy rainfall can lead
to over a million tonnes of untreated sewage
and rainwater legally discharging directly
into the rivers. Despite much improvement
in the Thames this is clearly unacceptable in
the 21st century.
5.5 It also fails to comply with requirements
of the Urban Waste Water Treatment
Directive 76 . This requires wastewater to be
collected and transported for treatment
(generally secondary) before discharge.
However, the Directive recognises that
overflows will occur because it is not
possible to construct collecting systems
and treatment plants that will treat
all wastewater under all conditions. It
therefore requires Member States to adopt
measures to limit pollution from storm
water overflows.
5.6 The Thames Tideway has a delicate oxygen
balance, particularly in the summer months.
A relatively small volume of freshwater
flowing over Teddington Weir together with
storm discharge from the CSOs and sewage
treatment works can adversely affect the
quality of the Tideway in three prime ways:
• A rapid drop in the dissolved oxygen puts
wildlife at risk
• A rise in the levels of pathogens can lead
to greater public health risks for those
using the watercourses directly
• Sewage-derived litter is offensive, and
reinforces the perception that the river is
lifeless (see paragraph 4.39).
Although only ten per cent of litter in the
Thames Tideway is sewage derived, it may
well be concentrated locally. In the summer
of 2007 skimmer boats were brought into
operation which removed most of the waterborne
sewage derived litter.
5.7 Concern is often expressed about the
health effects of storm discharges from the
CSOs. The City of London and the Health
Protection Agency undertook a study of
the health risks to recreational users of the
Thames between January 2005 and March
2006 77 . The stretch between Putney Bridge
and Kew Bridge was chosen for study
because of the concentration in recreational
use by 26 clubs. Less than one per cent
of days when river water samples were
taken were acceptable by the World Health
Organisation standard. However, the number
of cases of illness reported was considerably
lower than expected. One factor is likely to
be under-reporting. However, the report also
suggests that it is quite possible that users
have developed a measure of immunity or
improved tolerance to the pathogens.
5.8 The Thames Tideway Tunnels (comprising
the Thames Tunnel and the Lee Tunnel) have
been devised to mitigate these problems.
The Thames Tunnel will be 32.2 kilometres
long and will intercept all unsatisfactory
CSOs along the length of the tidal Thames
from west London to Beckton. The first

phase of work will be the construction of the
6.9 kilometre Lee Tunnel from Abbey Mills
to Beckton and the upgrading of Beckton
sewage treatment works. This will deal with
discharges from Abbey Mills that accounts
for up to 50 per cent of discharges from
the CSOs along the Tideway. A planning
application for the Lee Tunnel and extension
of the Beckton sewage treatment works was
submitted in May 2008, with construction
commencing in 2009 and completion by
2014. It is expected to deliver improvements
to the Olympic legacy by eliminating almost
all discharges into the River Lee.
5.9 The longer Thames Tunnel from west
London to Beckton is more complex than
the Lee Tunnel, requiring more extensive
design work, development effort and
stakeholder engagement. Construction is
Figure 5.2 Proposed Thames Tideway Tunnel
not therefore expected to start until 2012,
with completion in 2020. Improvements
to Beckton sewage treatment works are
necessary to allow rainwater and sewage that
will drain into the tunnels to be pumped out
and the sewage treated before discharge.
5.10 The present scheme was only adopted
after extensive study. The Thames Tideway
Strategic Study was set up in 2000 to
assess the environmental impact of the
intermittent discharges on the Thames
Tideway and to identify potential solutions
‘having regard to costs and benefits’.
The study reported in 2005 78 , and further
studies were undertaken in 2006. In March
2007 the government announced that it
supported the construction of a full-length
tunnel from Hammersmith to Beckton with
additional spur tunnel from Abbey Mills
73

74 The Mayor’s draft water strategy
Pumping Station to the Beckton Sewage
Treatment Works.
5.11 The Mayor strongly supports the construction
of the Thames Tideway Tunnel as a solution
to the problem of the CSO discharges, as well
as the proposed improvements to the sewage
treatment works. However, the Mayor has
a statutory duty to consider any planning
applications that are referred to him on their
individual merits.
Proposal 10 The Mayor will work with Thames
Water and other partners to support the
construction of the Thames and Lee Tunnels,
in a cost-effective way and minimising
disruption, as a means of greatly reducing
storm discharges from the combined sewer
system and improving the quality of the water
in the River Thames.
Flooding from sewers
5.12 Flooding from the foul sewers can result
from:
• Tidal or river floodwaters interfering with
the effective operation of the sewers and
becoming contaminated with sewage.
• The sewers can no longer cope with
the volumes of sewage (referred to as
overloaded sewers). Such flooding can be
aggravated by groundwater infiltrating into
the sewers, from the illegal connection
of private surface water drains to the foul
sewers, through the increased volumes of
sewage from new developments and by
runoff from increased impermeable areas.
• The sewers fail because of blockages,
collapses or pump failures.
5.13 Once sewage escapes from the foul sewer,
it can flood properties both internally or
externally. It can escape from the foul sewer
through drain gratings, manholes sanitary
fittings. It can flood houses and other
buildings, gardens, streets and open spaces.
It can also flood into the Underground
system as well as electricity supplies,
telecommunications and other critical
infrastructure.
5.14 Whatever the cause, flooding of this nature
is distressing to occupants of houses
affected and people living nearby, and is
generally far less predictable than river
or tidal flooding. In 1989, Thames Water
started a programme of works to reduce the
risk of flooding to some 10,000 properties
from its sewers, including engineering
solutions such as new underground pumping

stations and hydraulic solutions to alleviate
sewer flooding. In both 2006/07 and
2007/08 Thames Water removed over 500
properties from the risk of flooding once
or twice in 10 years, but 12,477 properties
remain at risk of flooding once in 20 years.
However, these were not all in London.
5.15 In the longer term, there is a need for a
better understanding of the sewer capacity,
and more effective controls on increased foul
water inputs to the sewer system. Defra’s
proposals in the Draft Flood and Water
Management Bill, discussed in paragraph
4.25, should help. Bad practices from both
domestic and commercial users, such as
sewer misconnections discussed below, can
also contribute to the overloading of sewers
leading to flooding.
5.16 There are circumstances where solving
the problem of sewer flooding can be
extremely expensive. Some modern practices
(for example, converting basements into
dwellings) can increase the incidence of
sewer flooding.
Misconnection of the foul sewer and
surface drains
5.17 In many cases the pollution in London’s rivers
comes from a much less obvious source than
factories, farms or industries. If a householder,
or professional plumber, inadvertently but
illegally connects household appliances
or waste pipes to the surface water drain
instead of the foul sewer, then foul water
can find its way into London’s streams, rivers
and canals without any prior treatment. The
misconnection of several houses or businesses
in the same area can cause damage to the
local watercourse. This is important for the
Mayor’s work to promote river restoration – it
is unsatisfactory to seek major funding to
restore the river’s structure and character if
the water quality continues to be severely
compromised.
5.18 Thames Water estimates that one in every
20 houses in London has a misconnection. In
some areas, this figure is considerably higher.
For instance in the Pymmes Brook catchment
in Barnet, it is more likely that one in every
ten houses has a misconnection.
5.19 During periods of wet weather, flow rates
are generally high enough to wash away
any signs of pollution. Yet when river flows
are low, the sewage matter is more visible.
Sewage in the river causes oxygen levels to
drop. In the more severe cases, the river can
no longer support the aquatic wildlife during
the pollution incident.
5.20 If a misconnection is the likely cause of
the pollution, then Thames Water and the
Environment Agency will try to find the
offending house(s). If successful, they will
notify the householder(s). At the same
time they will pass on the details to the
environmental health department of the
respective borough. An environmental health
officer will then check that the householder
has rectified the problem. Similarly, a
misconnection of the surface water drain to
the foul sewer can cause the foul sewer to
flood (see paragraph 5.12).
75

76 The Mayor’s draft water strategy
5.21 Currently, local authorities are the only
bodies with the powers to require a
householder to correct a misconnection.
If the householder does not put things
right within a specified time then the local
authority can have the repair work carried
out and require the householder to pay
the costs. The government now propose in
the Draft Flood and Water Management
Bill 79 to give sewerage companies similar
powers to those of local authorities to rectify
misconnections. This will cut out one step
in the process because water companies will
be able to deal with problems directly rather
than through local authorities. Though
the proposed changes in the draft bill are
principally aimed at misconnections from
households, the changes would enable water
companies to deal with misconnections to
surface water drains or to foul sewers from
any type of property.
Proposal 11 The Royal Institution of Chartered
Surveyors should consider including a survey
of sewer misconnections as part of the home
surveys at the time of sale.
5.22 The Environment Agency has prepared a
leaflet 80 showing how people can identify
whether their property has misconnections
and suggests some actions that people can
take, including asking surveyors to identify
misconnections in house surveys.
Fat, oil and grease
5.23 Fat, oil and grease (FOG) contribute
significantly to blockages in sewer
systems and these often result in flooding
of properties and/or the pollution of
watercourses. Although both domestic and
commercial customers produce FOG, it is
recognised that restaurants, takeaways
and other cooked food establishments
are probably the cause of most problems
( particularly when there are several such
establishments in a ‘High Street’ all draining
into the same sewer system.
5.24 Although there is guidance on grease
management from catering premises, illegal
disposal of commercial cooking oil in the
sewer system is a problem. This material
congeals on the surface of sewers and, if
not removed, will block sewers. If collected,
there are processes to convert the cooking
oil into biodiesel for use as a vehicle fuel.
This not only solves the problem in the
sewer system, but also can cut the emission
of greenhouse gas by replacing conventional
diesel fuel.
5.25 There is a long-established infrastructure in
the UK for the collection of used cooking oil
(UCO) from food establishments. However,
since December 2004, changes to legislation
has prohibited the use of UCO in the
production of animal feed and UCO therefore
no longer had much intrinsic value. For this
reason, many food establishments have to pay
for it to be taken away, greatly increasing the
risk of its being tipped into the sewer. While
UCO is only one constituent of FOG that can
cause blockages, it is produced in far greater
quantities than fat or grease and although it
may be liquid at room temperature or when
taken out of a deep-fryer, it can solidify once

mixed with cold water in the sewer. FOG
can also be a problem for local authorities
if it is illegally ‘dumped’ with domestic or
commercial refuse.
Wastewater management and energy
5.26 Used cooking oil (UCO) can be converted
into biodiesel and sold as a transport fuel. As
a direct replacement for diesel fuel distilled
from crude oil, it meets the government’s
Renewable Transport Fuel Obligation’s
sustainability and environmental criteria as
well as avoiding the problems described in
the previous paragraph. UCO is collected
from City Hall and the London Fire Brigade
Headquarters as well as from Transport for
London and Metropolitan Police catering
sites across London for recycling into
biodiesel. The London Waste and Recycling
Board is setting up a brokerage service
to link the sources of UCO to biodiesel
producers in order to promote recycling and
to encourage the use of biodiesel in public
sector transport fleets.
5.27 The treatment of sludge (see paragraph 5.29)
can provide an additional source of energy.
Mogden, Long Reach, Deephams, Hogsmill
and Beddington sewage treatment work
generate electricity by using sewage gas to
fuel gas engines. There is the potential to
increase the amount of electricity generated
and to export this to the public supply
network. Sewage gas can also be used as a
vehicle fuel, and there are many examples
of this being done around the world but not
currently in London. Utilising sewage gas,
which is mainly methane, in this way reduces
the release of this powerful greenhouse gas
to the atmosphere.
5.28 In the slightly longer term, sewage gas can
become an important source of non-fossil
fuel hydrogen for use in stationary fuel cells
and fuel cells used to power vehicles. There
have been a number of demonstrations of
sewage gas, after treatment, being used
to power fuel cells around the world but
none so far in the UK. The use of fuel cells
in vehicles have been very successfully
demonstrated by the three fuel cell
buses operating the RV1 route for three
years as part of the CUTE (Clean Urban
Transport for Europe) project. However, the
hydrogen used in this case is derived from
conventional fossil sources.
Sludge management
5.29 The EU and Defra consider the use of
sewage sludge on agricultural land as the
best practicable environmental option in
most circumstances. The use of sludge
on agricultural land supports the vision
through the goals of healthier soils and
wiser, sustainable use of natural resources.
However, evidence submitted to the House
of Lords Science and Technology Committee
review of Water Management by Professor
Joe Morris suggests that supermarkets,
mindful of the views of their customers, have
‘distanced themselves’ from crops grown
using sewage sludge as a fertiliser 81 . This
seems to indicate that there is decreased
rather than increased public confidence in
disposal of sludge to land, although this is
not the view of water industry professionals.
77

78 The Mayor’s draft water strategy
5.30 Thirty seven per cent of London’s sludge is
produced at Beckton, the largest of Thames
Water’s wastewater treatment sites, with
another 38 per cent produced at the next
two – Mogden and Crossness 82 (see Table
5.1 and Figure 5.1). Almost 50 per cent
of the digested sludge is recycled to land,
including a small amount of limed sludge
produced at Beckton and Crossness. Whilst
the use of sewage sludge on agricultural
land is considered to be the best practicable
environmental option, it can involve high
transportation costs. Over the next ten
years the company is looking to introduce
enhanced digestion at a number of its
sludge treatment centres. This will reduce
the volume of sludge as a result of solids
reduction and hence there will be less
dependence on the land-recycling outlet.
5.31 Additional capacity for the management of
sewage sludge will be needed as a result of
population growth and tighter environmental
standards. Thames Water has prepared a 25year
sludge strategy that favours processes
that (a) maximise energy recovery and (b)
minimise sludge volumes 83 . Where there is
suitable land bank availability, recycling sludge
to land remains the favoured option. To help
protect this outlet Thames Water anticipates
investing in sludge treatment to improve
product quality. However, in predominately
urban areas, the use of ‘thermal destruction
processes with energy recovery’, in other
words incineration, is thought likely to
be more appropriate, thus avoiding the
increased environmental impact and costs of
transporting the treated sludge to land.
5.32 In the longer term, the benefits of carrying
out co-digestion with other wastes, such as
municipal wastes, are attractive, particularly
from the point of view of increasing energy
production. However, the potentially negative
effects of increased traffic movements
required to transport additional material on
site, regulatory controls and the increased
operational complexity involved, would need
to be assessed on a site-by-site basis. The
London Plan states that the Mayor will work
in partnership with the boroughs and Thames
Water to ensure the timely provision of
appropriate new facilities at existing sewage
treatment works within London 84 .
5.33 The Mayor’s Municipal Waste Management
Strategy is now being reviewed. The Mayor
will work with Thames Water and with the
London Waste and Recycling Board to
identify any potential synergies between
solid waste and sewage waste management.
The Mayor will also work with Thames Water
to investigate ways in which the sludge
strategy can be developed to meet the
objectives and targets of the Climate change
mitigation and energy strategy, which he is

equired to prepare under the Greater London
Authority Act 2007, whilst meeting the
operational needs of Thames Water. A recent
study by National Grid 85 draws attention
to the significant potential for renewable
gas production in the UK. Whilst sewage
treatment is one of the smaller sources, it
would still make a worthwhile contribution.
Proposal 12 The Mayor will work with Thames
Water and other partners to identify ways in
which the management of sewage can provide
renewable energy and reduce emissions of
greenhouse gases. The Mayor encourages
Thames Water and other partners to identify
opportunities to use new technologies to
contribute towards the Mayor’s targets for
decentralised energy, particularly through the
production of biogas, and greenhouse gas
emissions reduction.
Odour nuisance
5.34 Sewage is produced as a by-product of
human existence and numerous industrial
processes and is by its very nature odorous.
In general, the older sewage treatment
works were built in areas that were well
away from where people lived and worked
and were not therefore designed specifically
to limit odour in the surrounding area.
Nevertheless, the operators of sewage
treatment works have taken account of
odour and generally operated their works so
that odour nuisance is controlled in so far as
the treatment processes allow.
5.35 Now, in many cases, housing and other
developments have significantly encroached
on the land around sewage treatment works
as well as around other waste management
facilities. This has greatly increased the
number of people affected by sewage works
odour. The public has become less accepting
of low-level nuisance from industrial
and similar activities, expecting a better
environment and believing that complaint
can lead to action, particularly from a
privatised industry. These factors have
contributed to a general perception that the
problem of odour nuisance from sewage
treatment works has been steadily increasing
over the last two decades.
5.36 Thames Water has carried out odour surveys,
and drawn up Odour Management Plans
for sites at risk of causing odour nuisance 86 .
At Crossness Sewage Treatment Works, a
permanent sludge liming plant equipped
with an odour control unit was completed
in 2006 and existing odour control units
were refurbished. The project to reduce
odour at Mogden Sewage Treatment
Works was completed in 2008 with covers
and equipment to extract air to odour
control units installed. An assessment of
the project carried out by an independent
odour specialist concluded that site odour
emissions had reduced by over 66 per cent
from 2005 levels.
79

80 The Mayor’s draft water strategy

6 Paying for water services
6.1 Understanding the history of the water
industry is important in understanding why
we pay for water in the way that we do.
There was much debate in 19th century
London over whether water should be paid
for through the rates (see paragraph 6.3) as a
public service or should be metered and paid
for according to the amount used. Eventually,
the argument that water should be a publicly
owned service – available on the basis of
Figure 6.1 Average water and sewerage bills 2008-09
Thames
Severn Trent
Northumbrian
Yorkshire
Industry average
United Utilities
Wessex
Anglian Water
D r Cymru
Southern
South West
Portsmouth
Cambridge
South Staffs
Southern
Dee Valley
Northumbrian
Bournemouth
Severn Trent
Veolia Three Valleys
Yorkshire
Bristol
Industry average
Sutton & East
Mid Kent
Essex & Suffolk
South East
United Utilities
D r Cymru
Tendring Hundred
Anglian Water
Thames
Folkestone & Dover
Cholderton
Wessex
South West
universal, constant provision and managed for
the good of the community – gained official
acceptance 87 . The Metropolitan Water Board
was established in 1903 to take over the
water services originally provided by private
companies in London.
6.2 The Metropolitan Water Board’s service area
covered the whole of the County of London
and the majority of the built up area at that
Average
sewerage bills
Average
water bills
£0 £50 £100 £150 £200 £250 £300
Industry average bill Companies supplying water in London

82 The Mayor’s draft water strategy
time. The Water Act 1973 amalgamated the
Metropolitan Water Board with many of the
other municipal and private water companies
in the Thames Valley to form the Thames
Water Authority. It was privatised in 1989.
Veolia Water Three Valleys, Essex & Suffolk
Water (now part of Northumbrian Water),
and Sutton & East Surrey Water continued to
operate in the private sector.
6.3 The majority of London households continue
to pay for their water and sewerage services
on the basis of the rateable value of the
property. The rateable value is the estimated
value of a property, based on the annual rent
it (with vacant possession) would fetch on
the open market. The rateable value was the
basis on which householders generally paid
for their local authority services until 1990.
Community Charge (frequently referred to
Table 6.1 Water use and related costs in eight European capital cities (2004)
City Average
individual
use
(m 3 /p/a)
Average
number of
people per
household
Drinking water
services
Average
bill (in
euros)
Share
of the
household
budget
as the poll tax) replaced it, and then later
Council Tax. Paying for water services is now
the only purpose for which domestic rateable
values are used. The introduction of meters
as the basis for charging for water, discussed
below, will affect how much households
have to pay, and any changes will be
judged against the current rateable value
based charges.
6.4 As explained in more detail in paragraph
6.24, there are two components to domestic
water customers bills. One part covers water
supply and the other sewerage services.
Figure 6.1 overleaf show the average bills
for customers of the companies serving
London relative to companies in other part
of England and Wales. The bills for sewerage
services are generally higher than the bills
for water supply.
Wastewater services Total
Average
bill (in
euros)
Share
of the
household
budget
Average
bill (in
euros)
Share
of the
household
budget
Amsterdam 57 2.3 237 0.8% 270 1.0% 506 1.8%
Athens 61 2.7 107 0.5% 64 0.3% 171 0.8%
Berlin 43 1.8 162 0.6% 227 0.8% 389 1.4%
London 54 2.4 169 0.5% 143 0.4% 312 0.9%
Madrid 61 2.9 135 0.5% 72 0.3% 207 0.8%
Paris 52 1.9 105 0.3% 124 0.3% 229 0.6%
Rome 104 2.6 114 0.4% 115 0.4% 229 0.8%
Stockholm 77 2.0 129 0.5% 192 0.7% 321 1.1%
Source: BIPE 88

6.5 Table 6.1 reproduces data from a study that
compared costs in eight European capital
cities in 2004. This shows London as below
average in terms of individual water use, at
the centre of the range of costs for drinking
water, and just below the mid-point for both
wastewater services and combined drinking
water and wastewater services.
Regulation of water services
6.6 Water Services Regulation Authority (Ofwat
– formerly the Office of Water Services) was
established as the economic regulator for
the privatised water industry in order to:
• Protect the interests of consumers,
wherever appropriate by promoting
effective competition.
• Ensure that the functions of each water
company (referred to in the legislation
as ‘undertakers’) are properly carried out
and that they are able to finance their
functions, in particular by securing a
reasonable rate of return on their capital,
• Ensure that companies with water supply
licences (ie those selling water to large
business customers, known as licensees)
properly carry out their functions.
Ofwat also has a general duty to consider
how the exercise of its various powers will
affect the environment and to contribute
towards achieving sustainable development.
Setting price limits
6.7 Ofwat sets price limits for each company
that allow the companies to finance their
functions. The current price limits were set
in 2004 (generally referred to as Periodic
Review 2004 or PR04) for the period
covering 2005-2010. The next set of price
limits, referred to as PR09, will be set later
this year to cover the period 2010-2015. The
government’s role in the periodic review is to
provide the national context of policies and
priorities for the water industry. This is done
through the Secretary of State’s Statutory
Social and Environmental Guidance to
the Water Services Regulation Authority
(Ofwat) 89 , which reflects the policies set out
in Future Water (see paragraph 1.5).
6.8 As part of the periodic review, each company
has a level of service set for its security of
supply, expressed in terms of the frequency
and duration of restrictions on use (such as
hosepipe bans) that it expects it will need
to impose to ensure that essential supplies
are maintained (see Table 2.6). Companies
set the level of service with reference to
customers’ willingness to pay, and Thames
Water carried out willingness to pay studies
with its customers in the summer of 2007 in
preparation for PR09 (see paragraphs 6.13).
6.9 Ofwat uses the concept of ‘headroom’ in
order to ensure that companies can fulfil
their duty to maintain water supplies.
Headroom is the buffer between supply and
demand when forecasting these for future
years. Water companies calculate how much
headroom they will need in a ‘normal’ and
a ‘dry’ year, and Ofwat then uses these
estimates to assess the overall security of
supply for each water company. Table 2.8
shows the security of supply index for
each company.
83

84 The Mayor’s draft water strategy
6.10 The price limits were set for Thames Water
by Ofwat under PR04 to allow it to:
• increase its maintenance of pipes and
sewers including the renewal of about
1,400 kilometres of water distribution mains
• progress improvements to security of
supply by developing a desalination plant
at Beckton, and to begin detailed planning
for a new reservoir in Oxfordshire
• install 63,000 optional meters and 49,000
selective meters, such as those installed
when there is a change of occupier, by
2009/10
• implement measures to reduce odour from
Mogden sewage treatment work
• reduce sewer flooding due to repeated
blockages at 3,700 properties
as well as to carry out other works to
improve the quality of its services 90 . The
Thames Tideway scheme (see paragraph
6.18) was not included as this will come
within the price determination to be
completed later this year.
6.11 Water companies submitted their business
plans for 2010-2015 to Ofwat in April
2009. These included their estimates of
the average customer bills that would be
necessary in order to finance their continued
provision of water and sewerage services,
taking into account factors such population
growth, meeting higher environmental
standards and improved efficiency. Table 6.2
shows the proposed average bills for the four
water companies serving London.
6.12 In July 2009 Ofwat issued its draft response
to the water companies’ proposals 92 . Ofwat
proposed a £14 or four per cent reduction
in average bills between 2010 and 2015. For
Thames Water it proposed no change in bills,
for Essex & Suffolk a nine per cent increase,
for Sutton & East Surrey an eight per cent
decrease and for Veolia Water Three Valleys
an 11 per cent decrease. There will be
further negotiations between the companies
and Ofwat, which will then issue its final
determination in November 2009. The
final determination will have a significant
influence on Thames Water’s ability to
reduce the high rate of leakage in London.

Customers’ willingness to pay
6.13 As noted in paragraph 6.8 above, Thames
Water carried out willingness to pay studies
in the summer of 2007 in preparation for
PR09. They took their existing levels of
service (which include water pressure,
hosepipe bans, odour and other standards)
and asked customers to choose between
several different packages of service with
different effects on their bills 93 . Overall
customers place a very high value on
maintaining the current level of service for
some services, notably:
• maintaining compliance with drinking
water standards
• reducing the number of properties affected
by flooding from sewers
• keeping the taste, appearance and odour
of tap water acceptable.
6.14 On the question of paying to improve
certain services, the clear top priorities for
customers were:
Table 6.2 Proposed water company average bills 2009-10 to 2014-15
2009 -
2010
• continuing to reduce the level of leakage
from water mains
• dealing with odour nuisance caused by
sewage treatment
• reducing the number of complaints about
the taste, colour or odour of tap water
• reducing problems with low water pressure.
There was a low priority placed on paying
for measures to reduce the frequency of
hosepipe bans and improving river quality.
Setting leakage targets
6.15 In 2002 Ofwat, Defra and the Environment
Agency jointly published a report on setting
leakage targets for water companies,
generally known as the ‘tripartite leakage
study’ 94 . The report recommended that
companies should use the economic level of
leakage (ELL) as a basis for setting targets.
As explained in paragraph 3.5, the ELL is the
level at which it would cost more to make
further reductions than to increase supply or
reduce demand by other means. Since then
Water Sewerage Combined Change
2014 -
2015
2009 -
2010
2014
-2015
2009 -
2010
2014 -
2015
Thames Water £178 £203 £118 £140 £296 £343 16%
Essex & Suffolk £165 £185 £118 £140 £283 £325 15%
Sutton & East Surrey £160 £201 £118 £140 £277 £341 23%
Veolia Water Three Valleys £155 £174 £118 £140 £273 £314 15%
Industry average £155 £173 £198 £214 £353 £387 10%
Note: It is assumed in this table that Essex & Suffolk Water, Sutton & East Surrey Water and Veolia Water Three Valleys
customers in London pay the average Thames Water sewerage charge
Source: The Independent Review of Charging for Household Water and Sewerage Services 91
85

86 The Mayor’s draft water strategy
the prolonged drought in the south and east
of England in 2005 and 2006 has highlighted
customer concern at high leakage levels at a
time when they were subject to restrictions
on their water use. Thames Water’s willingness
to pay studies suggests that consumers
believe current leakage levels in London to
be unacceptable and are prepared to accept
these higher costs.
6.16 Since then, a further review of this
approach to leakage target setting has been
undertaken by Ofwat and the Environment
Agency 95 which seeks to take into account
a wider range of costs and benefits.
However, none of this work takes account
of the particular conditions that prevail
in London. As noted in paragraph 3.5, for
example, no account is taken of the serious
damage caused to other infrastructure such
as the London Underground network by
leaks and burst mains 96 , and there is little
information on the costs to business 97 . Burst
mains and leakage repair causes serious
traffic congestion. Whilst mains renewal
in a busy street such as Tottenham Court
Road disrupts traffic in the short term, once
completed it should avoid problems for
decades. However, Thames Water’s view is
that beyond 2020 further leakage reduction
will become an increasingly expensive way
of balancing supply and demand because
the leakage reduction per kilometre of mains
replaced will be diminishing, given that the
mains with the worst leakage will largely
have been replaced 98 . Even so, the company
still expects to have the highest rate of
burst mains in England and Wales due to the
number of old cast iron mains that will still
be in-situ 99 .
6.17 Information provided in the Statement
of Response: Draft Water Resource
Management Plan indicates that the
overall rate of leakage will be reduced from
217 litres per property to day (l/p/d) in
2007/08 to 123 l/p/d in 2020-2025 and
then to 114 in 2030- 2035 100 . The Mayor
does not regard this as a satisfactory
objective after some 30 years of Victorian
Mains Replacement, Active Leakage Control
and customer supply pipe leakage reduction.
The water companies should be working
towards a target of 80 l/p/d across the
London Water Resource Zones by 2035.
This may not be economically justifiable
at present (see paragraph 3.11) but the
25-year time scale of Water Resources
Management Plan should allow for
significant improvements to be achieved in
the cost-effectiveness of leak reductions and
mains renewal. Londoners could reasonably
expect that once current street works are
completed, London will have a water supply
system that meets a good, if still not the
very best, international standard.
Thames Tideway tunnel and treatment
6.18 The various proposals for tackling the
problems caused by London’s combined
sewer overflows (CSOs) are discussed above
in paragraphs 5.3 to 5.11). The capital cost
of the work to be completed in the next
price review period, between 2010 and
2015, is £963 million 101 . This will see the
completion of the Lee Tunnel in 2014, and

the start of work on the Thames Tunnel.
Improvements to the Beckton Sewage
Treatment Works, to cope with the extra
wastewater transferred to the site, will be
carried out between 2015 and 2020 at a
capital cost of £165 million.
6.19 Thames Water’s final business plan,
submitted to Ofwat in April 2009, includes
investment proposals to construct the Lee
Tunnel and funding to undertake further
design and development for the Thames
Tunnel. Given the size and complexity of
Thames Tunnel, funding for its construction
will not be sought until further design and
development work has been completed.
Thames Water has adopted this approach
in order to minimise the effects on its
customers’ bills and ensure the most cost
effective approach to development.
6.20 Thames Water has sought an increase in
customer bills of 17.2 per cent between
2009/10 and 2014/15 102 . Over a quarter of
this increase is accounted for by expenditure
on the Tideway Tunnel. Customers who
receive their drinking water from other
companies but are within the Thames Water
sewerage area see an average increase in
their bills of £23 between 2009/10 and
2014/15, £13 of which will relate to the
Tideway Tunnel. As explained in paragraph
6.12 above, Ofwat’s draft response to
Thames Water’s business plan is that there
should be no increase in Thames Water’s
bills. Cost increases should be avoided unless
they are truly necessary at all times, and
particularly during a recession. Nevertheless,
the Mayor considers this scheme as
necessary to deal with pollution caused by
the combined sewer overflows along the
River Thames and in the lower River Lea.
Charging for water
6.21 The need to measure water use in order to
manage it adequately is a strong argument
in favour of moving away from the present
arrangement whereby most households are
charged for water on the basis of the rateable
value of the property to universal water
metering. In the light of increasing household
water demand, another argument in favour is
that it can help to conserve water. Research
has shown that household metering reduces
water use by between ten and 15 per cent
with larger peak demand savings 103 . It is not
surprising that people tend to use less water
when they pay for it according to the volume
used rather than on the basis of an assessed
charge. The view of the Mayor of London is
that all houses and flats should be metered,
with correct tariffs to protect vulnerable
groups. In a recent study carried out for the
Consumer Council for Water the vast majority
of consumers considered, at least initially that
‘pay for what you use’ tariffs were the fairest
way to pay for water 104 .
6.22 In 2008, the government announced an
independent review of water metering and
charging in its water strategy Future Water.
The review, being undertaken by Anna
Walker, is:
• examining the current system of charging
households for water and sewerage
services, and assess the effectiveness and
87

88 The Mayor’s draft water strategy
fairness of current and alternative methods
of charging
• considering social, economic and
environmental concerns
• making recommendations on any actions
that should be taken to ensure that
England and Wales has a sustainable and
fair system of charging in place. This could
include changes to current legislation and
guidance.
An interim report, published in June
2009 105 , says that, ‘We have concluded that
charging by use of water meets more of the
fairness principles than any other method of
charging’.
6.23 However, there are various arguments
against metering. One argument is that there
are cheaper ways of conserving water. For
example, low-flush toilets reduce total water
consumption by nearly as much as metering,
but low-flush toilets cost less than metering
does. Opponents of metering also argue that
most of the cost in providing water does not
depend on the quantity of water used, so
charging on the basis of use is irrelevant. Yet
the quantity of water used has an impact on
cost; the social costs of additional marginal
use are often high. Likewise not charging for
use means that there is no incentive for less
wasteful use.
6.24 An unmeasured water bill has two
components: a standing charge (the same
for each household) and an additional
charge based on the rateable values of the
house or flat. Some water companies make
the standing charge the largest part of the
bill, while others make the rateable value
the main part. Domestic water consumers
also pay for the three sewerage services –
highway drainage, surface water drainage
(run-off from a property), and sewage
collection. The surface drainage charge
to households is rebated where it can be
shown that the rainwater pipes are not
connected to the public sewer. Highway
drainage is usually levied as a flat fee as it
bears no relation to the other services and is
unrelated to household size or consumption
of services. It is a service to the general
public rather than to individual households.
The Walker Review is seeking views on
basis on which costs can be allocated fairly
between the different sewer services.
6.25 Since 2000, households have had the right
to the free installation of a meter on request.
Water companies can also meter customer
on change of occupancy. In areas of water
stress, companies have powers to compulsory
meter (as happened with Folkestone and
Dover Water Services in March 2006 106 ) but
this process is complex. In August 2007 Defra
announced that water companies in areas of
serious water stress (see paragraph 2.6) would
be able to seek compulsory water metering
as part of their 25-year Water Resource
Management Plans 107 .
6.26 Whilst there is evidence to support the
view that water metering leads to a
reduction in water consumption, there is
also concern that water metering could
impose an additional financial burden on
some low-income households. Fuel poverty

is a fairly well defined concept, referring
to households that cannot afford to keep
adequately warm at reasonable cost.
Reasonable cost is taken as ten per cent
of household income. The concept of
‘water poverty’ is less widely accepted but,
where used, usually refers to households
spending more than three per cent of
household income on water services. The
Walker Review team’s view is that while
water spend expressed as a percentage of
income might be a useful indicator of the
relationship between customer bills and
incomes over time, it is not suitable to
be used as a trigger for assistance. This is
because any percentage figure would be
set at an arbitrary level, unrelated to actual
water consumption or need, and would not
facilitate very targeted help 108 .
6.27 The Mayor and the Environment Agency
have jointly commissioned a study of the
likely social effects of the widespread
introduction of domestic water metering in
London and in the wider area of water stress
in the south east and east of England 109 . This
suggests that:
• Increasing the proportion of households
that have water meters will result in some
households paying more and some paying
less for their water.
• For most household the increase or
reduction in the cost of water will be less
than £20 per annum.
• Half the households with the lowest
ten per cent of income already spend more
than three per cent of their household
income on water, and the proportion
is likely to increase slightly as metering
becomes more widespread.
• The introduction of water meters will have
varying effects on costs in different parts
of London because of differences in the
types of housing, sizes of households and
levels of income.
• A tariff that relates the metered water
charge to the Council Tax band of the
property is likely to provide the greatest
protection to low income households.
The results of this study are being published
concurrently with this strategy, and will be
submitted to the Walker Review.
6.28 Although not part of this study, another
way of protecting vulnerable households
affected by the widespread introduction
of water meters is to help them to reduce
their water use through efficiency measures.
Potential savings in water and energy costs
for an average household are shown in Table
3.3, and can more than offset any cost
increases resulting from the introduction of
water meters. Although the Mayor’s retrofit
programme (see Chapter 3) will focus on
energy efficiency, it should also help many
households at risk of water poverty.
6.29 There is particular concern that water
metering of large low-income households
could lead them to cut back on essential
uses, such as on personal hygiene. There is
some evidence to support this concern 110,111 ,
although attempts to prove that this leads to
higher rates of disease have failed to show a
link. Nevertheless adequate water is vital to
halting the chain of infection and therefore a
89

90 The Mayor’s draft water strategy
basic minimum for essential hygiene should
be available to all at an affordable price.
6.30 For those households with a high essential
water use, for example as a result of a
medical condition, it is possible to reduce
their charges through targeted policies.
In April 2000, the government introduced
a vulnerable groups scheme 112 that caps
the bills of those identified as having high
essential water use. People may otherwise
be afraid to turn on their taps, possibly
compromising their health and the health
of others, because of worries about paying
their bill. The vulnerable group tariff,
called WaterSure, applies to those with a
water meter, in receipt of certain incomerelated
benefits, and who have a basic high
water use. It does not assist low-income
households with high water use solely as a
result of the size of the household.
6.31 Proposal 3 above stresses the importance of
tariff arrangements that protect vulnerable
and low-income households as part of the
programme for introducing water meters
throughout London.

Appendix
Notes and references
Web addresses for documents are correct as of
12 July 2009.
1 Secretary of State for Environment, Food
and Rural Affairs. 2008. Future Water:
The Government’s new water strategy for
England. Cm 7319. London: Department
of Environment, Food and Rural Affairs.
Available at: http://www.defra.gov.uk/
environment/water/strategy/pdf/futurewater.pdf
2 European Parliament and Council. 2000.
Directive 2000/60/EC of the European
Parliament and of the Council of 23
October 2000 establishing a framework
for Community action in the field of water
policy. Official Journal, L327, 22.12.2000,
p. 1-73. Available at: http://ec.europa.eu/
environment/water/water-framework/
index_en.html
3 Information on The London Plan is available
at: http://www.london.gov.uk/
thelondonplan/
4 Mayor of London. 2008. The London
Plan (consolidated with Alterations since
2004). London: Greater London Authority.
Available at: http://www.london.gov.uk/
thelondonplan/thelondonplan.jsp.
5 Mayor of London. 2009. A new plan for
London: Proposals for the Mayor’s London
Plan. London: Greater London Authority.
Available at: http://www.london.gov.uk/
mayor/publications/2009/05/london-planinitial-proposals.jsp
6 Mayor of London. 2008. The London climate
change adaptation strategy. London: Greater
London Authority. Available at: http://www.
london.gov.uk/mayor/publications/
2008/08/climate-change-adapt-strat.jsp
7 Mayor of London. 2009. London Housing
Strategy. London: Greater London Authority.
Available at: http://www.london.gov.uk/
mayor/housing/strategy/index.jsp
8 Mayor of London. 2009. Transport Strategy
Statement of Intent. London: Greater
London Authority. Available at: http://www.
london.gov.uk/mayor/publications/2009/
docs/transport-strategy.pdf
9 Greater London Council. 1985. London’s
Decaying Infrastructure: The Way Ahead.
London: Greater London Council.
10 Environment Agency. 2001. Water resources
for the future, a strategy for Thames Region.
Reading: Environment Agency. Summary
available at: http://www.environmentagency.gov.uk/static/documents/Research/
wr_thames.pdf
11 Environment Agency. 2007. Areas of
water stress: final classification. Reference
GEHO1207BNOC-E-E. Bristol: Environment
Agency. Available at: http://www.
publications.environment-agency.gov.uk/
pdf/GEHO1207BNOC-e-e.pdf
12 Environment Agency. 2001. A scenario
approach to water demand forecasting.

92 The Mayor’s draft water strategy
Worthing: National Water Demand
Management Centre, Environment Agency.
13 Barucq C, Guillot J-P and Michel F. 2006.
Analysis of Drinking Water and Wastewater
Services in Eight European Capitals. Issyles-Moulineaux,
France: BIPE. Available
at: http://international.stockholm.se/
InternationalGlobal/Stockholm%20by%20
theme/A%20sustainable%20city/BIPE%20
report%20April%202006.pdf
14 See item 13 above.
15 OCED. 2000. The Price of Water: Trends in
OECD Countries. Paris: OECD. Summary
paper available at: http://www.oecd.org/
dataoecd/21/1/1934075.pdf
16 Secretary of State for Environment, Food
and Rural Affairs. 2009. Draft Flood and
Water Management Bill. Cm 7582. London:
Department of Environment, Food and
Rural Affairs, p 94. Available at: http://
www.official-documents.gov.uk/document/
cm75/7582/7582.asp
17 Ofwat 2008 Water supply and demand
policy – Appendix 1: Water efficiency targets
2010-11 to 2014-15. Birmingham: Ofwat.
Available at: http://www.ofwat.gov.uk/
pricereview/pap_pos_pr09supdempolapp1.
pdf
18 See note 16 above, p 116.
19 Environment Agency. 2007. Water for the
Future- Managing water resources in the
South East of England. GEHO1007ENKA-
E-E. Bristol: Environment Agency.
20 Further information is available at: http://
www.thameswater.co.uk/cps/rde/xchg/
corp/hs.xsl/2550.htm
21 Thames Water. 2008. Water – planning
for the future. Draft Water Resources
Management Plan. Volume 1 – Summary
Overview. Reading: Thames Water Utilities
Limited, p. 20-24. Available at: http://www.
thameswater.co.uk/cps/rde/xbcr/corp/
drwmp-01-summary-overview.pdf
22 Environment Agency. 2008. The
Environment Agency’s representation
on Thames Water draft water resources
management plan. Bristol: Environment
Agency. Available at: http://publications.
environment-agency.gov.uk/pdf/
GEHO0808BOOB-e-e.pdf?lang=_e
23 Atkins, W S. 1993. Seven-Thames Transfer
Feasibility Study. Final Report Volumes 1 and
2. Reading: National Rivers Authority
24 Environment Agency. 2006. Do we need
large scale transfers for south east England?
Bristol: Environment Agency. Available at:
http://www.environment-agency.gov.uk/
static/documents/Research/grid_1464452.
pdf
25 Understanding London’s Urban Climate.
London: Greater London Authority,
forthcoming.

26 RPS Water. 2007. Providing best practice
guidance on the inclusion of externalities
in the ELL calculation. Birmingham: Ofwat.
Available at: http://www.ofwat.gov.uk/
regulating/reporting/gud_pro_ellcalcmain.
pdf
27 Taylor C. 2005. ‘A drain on resources’. New
Civil Engineer, 19 May 2005, pp. 33-34.
28 Artesia Consulting. 2009. Leakage target
setting in London. London: Greater London
Authority. Available at: http:// www.london.
gov.uk/mayor/environment/water/docs/
leakage-target-setting.pdf
29 Thames Water. 2009. Statement of
Response: Draft Water Resource
Management Plan. Reading: Thames Water.
Available at: http://www.thameswater.
co.uk/cps/rde/xchg/corp/hs.xsl/8746.htm
30 See note 29 above, Table 27.
31 Tokyo Metropolitan Government. 2005.
Leakage prevention in Tokyo. Tokyo:
Bureau of Waterworks, Tokyo Metropolitan
Government.
32 Kitching R. 2005. ‘Keep on running’. New
Civil Engineer, 19 May 2005, pp. 30-31.
33 Further information on the water main
replacement and rehabilitation programme
in Hong Kong is available from the Water
Supplies Department, Government of
the Hong Kong Special Administrative
Region, at: http://www.wsd.gov.hk/
en/replacement_and_rehabilitation_
programme_of_water/index.html
34 Mayor of London. 2009. Capital code to
cut congestion. Press Release 181, 16 April.
London: Greater London Authority. Available
at: http://www.london.gov.uk/view_press_
release.jsp?releaseid=21697
35 Further information is available at: http://
www.thameswater.co.uk/cps/rde/xchg/
corp/hs.xsl/4646.htm
36 Herrington P. 1996. Pricing water properly.
Discussion Papers in Public Sector
Economics No. 96/6. Leicester: University of
Leicester.
37 Ove Arup and Partners. 2007. Retrofitting
water meters into multiple-occupancy homes
London: Greater London Authority. Available
at: http://www.london.gov.uk/mayor/
environment/water/docs/meters-multipleoccupancy-homes.pdf
38 See note 37 above.
39 Waterwise. 2007. International experiences
of sub-metering: An analysis of four case
cities to inform planning for domestic
metering in the Greater London Area.
London: Greater London Authority. Available
at: http://www.london.gov.uk/mayor/
environment/water/docs/internationalexperiences-sub-metering.pdf
40 Pie chart data based upon information
given in: Environment Agency. 2007.
93

94 The Mayor’s draft water strategy
Assessing the cost of compliance
with the code for sustainable homes.
Reference SCHO0107BLTR-E-P. Bristol:
Environment Agency. Available at:
http://www.environment-gency.
gov.uk/static/documents/Business/
scho0107bltree_1746081.pdf
41 CLG. 2006. Code for Sustainable
Homes. London: Communities and Local
Government. Available at: http://www.
planningportal.gov.uk/uploads/code_ for_
sust_homes.pdf
42 See note 41 above.
43 CLG. 2007. Homes for the future: more
affordable, more sustainable. London:
Communities and Local Government.
Available at: http://www.communities.gov.
uk/publications/housing/homesforfuture
44 See the report referred to in note 40 above.
45 Cyril Sweett. 2007. A cost review of the
Code for sustainable homes. London: English
Partnerships. Available at: http://www.
housingcorp.gov.uk/upload/pdf/Code_for_
Sustainable_Homes_050407.pdf
46 Sustainable Development Commission.
2006. Stock Take: delivering improvements
in existing housing. London: Sustainable
Development Commission. Available at:
http://www.greenspec.co.uk/documents/
drivers/Stock_Take_UK_Housing.pdf
47 Halifax. 2007. ‘Nation of movers and
improvers’. Halifax Press Release 8
September 2007.
48 The London retrofitting package was based
upon the proposals outlined in: Environment
Agency. 2007. Water Efficiency in the
South East of England: Retrofitting existing
homes. Bristol: Environment Agency.
Available at: http://www.environmentagency.gov.uk/static/documents/Leisure/
retrofittinghomes_1751501.pdf
49 Arup. 2008. Your home in a changing
climate. London: Greater London Authority.
Available at: http://www.london.gov.uk/
trccg/docs/pub1.pdf
50 See note 49 above.
51 Environment Agency. 2008. Greenhouse
gas emissions of water supply and
demand management options. Science
Report – SC070010. Bristol: Environment
Agency. Available at: http://publications.
environment-agency.gov.uk/pdf/
SCHO0708BOFV-e-e.pdf
52 See note 4 above.
53 See note7 above.
54 The non-service sectors includes
construction, manufacturing of clothes,
electronic & electrical equipment, plastics,
metal production, and food manufacturing.
The service sector includes retail, hotels,
banking and finance, schools and hospitals.

55 Further information is available at: http://
www.envirowise.gov.uk/uk/Topics-and-
Issues/Water.html
56 Further information is available at: http://
www.eca-water.gov.uk/
57 Environment Agency. 2007. Towards
water neutrality in the Thames Gateway.
Science report: SC060100/SR3. Bristol:
Environment Agency. Available at: http://
publications.environment-agency.gov.uk/
pdf/SCHO1107BNMC-e-e.pdf?lang=_e
58 Brown R, Palmer A. 2004. Water reclamation
standard: Laboratory testing of systems
using grey water. Bracknell: BSRIA. Available
at: https://infonet.bsria.co.uk/booksdownloads/details/?i=67285
59 Foster, C et al. 2006. The Environmental
Impact of Food Consumption and
Production. London: Department for
Environment, Food and Rural Affairs.
Available at: http://randd.defra.gov.uk/
Document.aspx?Document=EV02007_4601_
FRP.pdf
60 Gummer, J (Chairman). 2007. Blueprint
for a Green Economy: Submission to the
Shadow Cabinet. London: Conservative
Party. Available at: http://www.
qualityoflifechallenge.com/documents/
fullreport-1.pdf
61 Baca Architects, et al. 2009. The LifE
handbook: Long-term initiatives for floodrisk
environments. Bracknell: IHS BRE Press.
62 CLG. 2009. Code for Sustainable Homes:
Technical guide. London: Communities and
Local Government. Available at: http://
www.planningportal.gov.uk/uploads/code_
for_sustainable_homes_techguide.pdf
63 The Town and Country Planning (General
Permitted Development) (Amendment) (No.
2) (England) Order 2008. SI 2008 No. 2362.
Available at http://www.opsi.gov.uk/si/
si2008/pdf/uksi_20082362_en.pdf
64 See note 16 above, pp 41-51.
65 Reacher, M et al. 2004. ‘Health impacts of
flooding in Lewes: a comparison of reported
gastrointestinal and other illness and
mental health in flooded and non-flooded
households’ Communicable Disease and
Public Health, 7(1) March 2004. Available at:
http://www.hpa.org.uk/web/HPAwebFile/
HPAweb_C/1213773807525
66 Environment Agency. 2009. TE2100
Plan – Consultation Document. London:
Thames Estuary 2100, Environment Agency.
Available at: http://www.environmentagency.gov.uk/research/library/
consultations/106100.aspx
67 CLG. 2006. Planning Policy Statement 25:
Development and Flood Risk. London:
Department for Communities and Local
Government. Available at: http://www.
communities.gov.uk/publications/
planningandbuilding/pps25floodrisk
68 See note 6 above.
95

96 The Mayor’s draft water strategy
69 Pitt, Sir Michael. 2008 (chair). The Pitt
Review: Lessons learned from the 2007
floods. London: Cabinet Office. Available
at: http://archive.cabinetoffice.gov.uk/
pittreview/ thepittreview/final_report.html
70 Defra. 2008. ‘Private sewers and drains
transferred to water company ownership’
News Release 15 December 2008. Available
at: http://nds.coi.gov.uk/content/detail.asp
?ReleaseID=387555&NewsAreaID=2&Naviga
tedFromSearch=True
71 See note 16 above, p 105.
72 Kucharek, Jan-Carlos. 2007. ‘Underground
assets’. RIBA Journal, June 2007, pp
34-36. Available at: http://demos.
constructingexcellence.org.uk/userimages/
Attachment586.pdf
73 See note 2 above
74 Further information is available at: http://
www.environment-agency.gov.uk/research/
planning/33106.aspx
75 European Council. 1991. Council Directive
91/271/EEC of 21 May 1991 concerning
urban waste-water treatment Official
Journal, L135, 30.5.1991, pp. 40-52.
Available at: http://ec.europa.eu/
environment/water/water-urbanwaste/
directiv.html
76 See note 75 above.
77 Lane C, Surman-Lee 5, Sellwood J and
Leethe J. 2007. Thames recreational users
study. London: City of London Corporation.
Available at: http://www.hpa.org.uk/web/
HPAwebFile/HPAweb_C/1194947405865
78 Copies of the Thames Tideway Strategic
Study reports are available at: http://www.
thameswater.co.uk/cps/rde/xchg/corp/
hs.xsl/6070.htm
79 See note 16 above, p 106.
80 Environment Agency. Undated. Are YOU
polluting rivers and streams? (leaflet).
Bristol: Environment Agency. Available at:
http://www.environment-agency.gov.uk/
homeandleisure/pollution/water/31424.
aspx
81 House of Lords Select Committee on Science
and Technology. 2006. Water Management.
Eighth Report HL Paper 191-I. London:
The Stationary Office, p.97. Available at:
http://www.publications.parliament.uk/pa/
ld200506/ldselect/ldsctech/191/191i.pdf
82 Thames Water. 2008. Thames Water’s 25year
Sludge Strategy. Reading: Thames
Water Utilities Limited, Table 3. Available at:
http://www.thameswater.co.uk/cps/rde/
xchg/corp/hs.xsl/6315.htm
83 See note 82 above.
84 See note 4 above, p. 217.

85 National Grid. 2009. The potential for
Renewable Gas in the UK. National Grid.
Available at: http://www.nationalgrid.com/
uk/Media+Centre/Documents/biogas.htm
86 Thames Water. 2007. Placing the
environment and community at the heart of
everything we do. Reading: Thames Water
Utilities Limited, p. 14. Available at: http://
www. thameswater.co.uk/cps/rde/xbcr/
corp/csr-reports-corporate-responsibilityreport-200607-040907.pdf
87 Trentman, F. 2007. Liquid Politics: the
historic formation of the water consumer.
Culture of Consumption Findings. London:
Birkbeck College. Available at: http://www.
consume.bbk.ac.uk/research/trentmann.
html
88 See note 13 above.
89 Defra. 2008. Statutory Social and
Environmental Guidance to the Water
Services Regulation Authority (Ofwat).
London: Defra. Available at: http://www.
defra.gov.uk/environment/water/industry/
review/pdf/ofwat-guidance080922.pdf
90 Ofwat. 2004. Future water and sewerage
charges 2005-10 : Final Determinations.
Birmingham: Ofwat, pp. 80-81. Available at:
http://www.ofwat.gov.uk/legacy/aptrix/
ofwat/publish.nsf/Content/pr04fd.html
91 The Independent Review of Charging for
Household Water and Sewerage Services.
2009. Interim Report. London: Defra.
Available at: http://www.defra.gov.uk/
environment/water/industry/watercharging-review/
92 Ofwat. 2009. ‘Ofwat holds bill down for
customers’. News release PN 03/09 23
July 2009. Birmingham: Ofwat. Available
at: http://www.ofwat.gov.uk/pricereview/
pr09phase3/prs_pn0309_pr09dd.pdf
93 Thames Water. 2008. Taking Care of Water.
Reading: Thames Water Utilities Limited, p.
14. Available at: http://www.thameswater.
co.uk/cps/rde/xbcr/corp/taking-care-ofwater-final-report-2mb-131207.pdf
94 Tripartite Group. 2002. Leakage target
setting for water companies in England and
Wales. Birmingham: Ofwat. Available at:
http://www.ofwat.gov.uk/publications/
commissioned/rpt_com_tripartitestudysum.
pdf
95 Marshallsay, D et al. 2007. Alternative
approaches to leakage target setting: final
report. Birmingham: Ofwat. Available at:
http://www.ofwat.gov.uk/regulating/
reporting/rpt_com_leakmethrev_alternative.
pdf
96 See note 27 above.
97 See note 28 above.
98 See note 29 above, p.122
99 Thames Water. 2008. Water – planning
for the future: Draft Water Resource
97

98 The Mayor’s draft water strategy
Management Plan. Volume 2 – Main Report.
Reading: Thames Water, p. 187 Available at:
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